By Mark Savage
BBC News entertainment reporter
Glastonbury organiser Michael Eavis says he has booked "a black American headliner" in an attempt to attract a younger audience to this year's festival.
Recent headliners include Paul McCartney, Radiohead and Moby
The annual music event's line-up is traditionally kept under wraps until the gates open, so fans won't find out who the artist is until June.
But who are the contenders to be the main act at the UK's biggest festival?
Who is he? Egotistical rap supremo, who last year completed his trilogy of education-themed hip-hop albums.
West's hits include Stronger and Through The Wire
Festival form: Kanye played last year's V Festival and delivered a short greatest hits set at the influential US festival Coachella in 2006. He has also won rave reviews for his recent world tour, which hit the UK in November.
Crowd-pleasing anthem: The Ray Charles-sampling Gold Digger, from Kanye's second album Late Registration, is a club favourite. The song was also covered by Glastonbury veterans The Automatic.
Will he play Glastonbury: Kanye's recent forays into electronic music would seem perfect for the Sunday-night slot, which is traditionally more dance-orientated.
While his world tour has drawn to a close, he has played one-off special concerts before, including an invitation-only gig at Abbey Road studios with a full symphony orchestra.
Who is she? Globe-straddling R&B diva, with a stunning 10 Grammy awards lined up on her mantelpiece.
Beyonce began her career with r&b trio Destiny's child
Festival form: Beyonce was the main attraction at two festivals in 2007 - as a singer at the Essence Music Festival in New Orleans, and an actress at the Cannes Film Festival.
Crowd-pleasing anthem: Too many to mention - but Crazy In Love, Survivor and Beautiful Liar are among her UK chart-toppers.
Will she play Glastonbury: The singer is in the studio working on her third solo album, which she is due to be promoting over the summer. But her pop sensibilities might be too mainstream for the Glastonbury audience.
Who is he? Record label boss, clothes designer, rap star and Beyonce's boyfriend.
Jay- announced his retirement in 2003 before coming back in 2006
Festival form: Before his brief retirement from hip-hop, Jay-Z was the Prince of Wales' special guest at the 2004 Prince's Trust Urban Music Festival.
Crowd-pleasing anthem: The rapper's signature track Izzo (Hova) is a fan favourite, but he has more than a decade's worth of hits to choose from.
Will he play Glastonbury: Michael Eavis has hinted his headliner hails from New York, which would make Jay-Z a frontrunner.
The rapper is also known to be good friends with former Glastonbury headliners Coldplay - with Chris Martin joining him on stage at the Royal Albert Hall two years ago. Maybe the singer has put in a word for the good people at Worthy farm.
Who is she? A 19-year-old Barbadian bombshell, based in the US, whose third album Good Girl Gone Bad has established her as a global star.
Rihanna's Umbrella was the second-biggest selling single of 2007
Festival form: She played Nigeria's ThisDay Festival and Radio One's One Big Weekend last year, and has stadium experience from the Tokyo leg of Live Earth.
Crowd-pleasing anthem: All-conquering number one hit Umbrella - an appropriate anthem for Glastonbury's famously inclement weather.
Will she play Glastonbury: Rihanna would definitely draw in younger audiences, but she is probably too inexperienced to be given the coveted headline slot.
Who is he? Super-producer Timbaland is the mastermind behind Justin Timberlake, Nelly Furtado, Aaliyah and Missy Elliot. Last year, he stepped out from behind the mixing desk to release his own top 10 album, Shock Value.
Timbaland is rumoured to be releasing a new album in the summer
Festival form: None to speak of, but the rapper spent the majority of 2007 on Justin Timberlake's Futuresex / Loveshow world tour.
Crowd-pleasing anthem: Justin Timberlake's SexyBack would be a sure-fire arms-in-the-air Glastonbury moment.
Will he play Glastonbury: Unlikely, given his lack of live experience. But if he could bring along the acts he's worked with - a list which now includes Madonna and Elton John - he would be a major draw.
Who is he? The pint-sized purple purveyor of pop, who spent a majestic 21 nights at London's O2 arena last year.
Prince was rumoured to be the Glastonbury headliner in 2005
Festival form: Prince tends to play his own concerts, but after more than 30 years on stage he would have very little trouble getting the Glastonbury crowd on their feet.
Crowd-pleasing anthem: He rehearsed 150 songs for his O2 residency, with greatest hits like Purple Rain and Raspberry Beret interspersed with more recent tracks like Musicology.
Will he play Glastonbury: Michael Eavis has spoken of his attempts to get Prince to the festival before, but his desire to attract younger audiences could rule the rock legend out of the running.
You sent your views on the mystery Glastonbury headliner.
I hope it's Prince. I think it will be Kayne West though. In my opinion Prince is a better musician and performer.
Andrew Sekula, Newquay
MC Hammer should play Glastonbury. He would rock the place. Hammer Time!
Tom Sky, London
If Jay-Z came with a backing band like his unplugged album had, he would do an awesome set indeed.
Rihanna is not American, so assuming that Michael Eavis's statement is correct she is ruled out.
Well I went to the V Festival last year and Kanye was there. The crowd went mad, so I think he is definitely top of my list for headlining!!! I know I'll be attempting to do the robot to Stronger! Whoop Whooooo!
Despite them both being incredible neither Stevie Wonder nor Prince would pull in a young audience. My first thought was Kanye West. If it's the Sunday night then I imagine he'd fit well with the usual dance night. I believe Kylie's diary is booked that weekend but there's no tour or promo that has been mentioned so I imagine she's headlining one of the nights too.
Why not Michael Jackson? I can imagine the muddy hordes getting down to Billy Jean, Thriller, The Way You Make Me Feel, etc. Could be the ultimate comeback.
Tim Hooper, Cambridge, UK
Can only really see it being Kanye. The only other possibility from that list would be Rihanna, but her pop leanings will more than likely rule her out of headlining, although she should still fit in well lower down the bill. As for the rest of the festival, presuming that Radiohead play the Saturday slot, that leaves Friday wide open, as I don't know who's around to play it. Coldplay?
Martin, London, England
I think it has to be Prince. He's an amazing live performer and no matter how old you are your gonna love his stuff... Prince has my vote all the way!
Sarah, St. Thomas, Swansea
Stevie Wonder all the way - material, talent, experience. You cannot touch him... The greatest musical performer/artist of our generation. Made for Glastonbury. But it will probably be Kanye West - Jesus Walks at dusk with that beat and the crowd going for it could be special.
John Lloyd, Liverpool
Wu Tang Clan would draw a younger crowd, plus they have a new album out.
Alicia Keys is a must - great new album, brilliant live act and a string of hits. She also communicates well with her live audience. Maybe not a headliner, but she would certainly be a good choice somewhere in the line-up.
Tony Steele, Burke Virginia, USA
It's got to be Kanye, but why does Eavis keep going on about getting a younger audience? Glastonbury is for all ages! I was in the crowd last year watching The Who and there were 20-year-olds singing along - and they knew the words! If you love music does it matter what age you are?
If you frequent a few festivals you'll know the more mainstream the headline act is the more trouble there is! Glastonbury has always had a good mix of people young and old.
Enough old people to stop it feeling like a school disco and enough young people to keep it fun.
David, Milton Keynes
It's gotta be Brian May. Most underrated hip hop artist since Marti Pellow.
Bob Duffield, Brighton, UK.
Rihanna is a rising superstar and on that premise should be given the headliner slot. She's also the only contender from a small island state and that makes her extra special.
Rihanna, St. John's Antigua
I go every year and would quite like to see Alicia Keys.
Andy Reed, Wells (near Glastonbury), UK
Michael Jackson, no doubt about it. It would be nice to see the response of the crowd when they see him moonwalking down the stage.
Nanne, Nijmegen, Netherlands
I think it will be Will Smith. He has said that he is going to tour this year and concentrate on his music. And I think he would appeal to everyone. Can you imagine if the sun comes out and they launch into Summertime..?
Black Eyed Peas, Outkast, Pharrell Williams, Dr. Dre, Asian Dub Foundation, 50 cent, Snoop Dogg... There are so many artists you have neglected to mention who would draw a young crowd and still fit Glastonbury!
Saidhbhin, Barcelona, Catalunya.
My immediate thought was Kanye West - and if I'm lucky enough to get a ticket, I'd certainly consider watching him as he is a great live act, although he's not my usual taste in music.
Becky Simms, Oxford, UK
Stevie Wonder.... None of the above artists (aside from Prince maybe) are Glastonbury headline material.
Lawrence Treadgold, London