More4, Channel 4's so-called "adult entertainment" channel, was launched three weeks ago. Now, in quick succession, we've got Sky Three and ITV4 - two more entertainment offerings from major UK broadcasters which already have several channels.
By Torin Douglas
BBC News media correspondent
The main broadcasters now have "families" of free-to-air channels
Why are there all these launches, when millions of viewers already have several hundred channels to choose from?
And aren't the new channels all competing for the same niche audience - the young adults so beloved of advertisers?
The first question can be answered in a single word - Freeview.
The digital terrestrial TV service - which offers several dozen channels with no need for a monthly subscription - has proved a huge success, selling around six million boxes so far.
This has prompted a change of strategy, not just at the terrestrial companies ITV and Channel 4 but also at the satellite broadcaster Sky.
A few years ago, ITV and Channel 4 believed the future of multichannel television lay in pay-channels, like those on the Sky platform.
ITV's owners launched ITV Digital - a pay service that tried to compete with Sky by offering films, drama and football, including several channels under the Granada and Carlton brand names.
More4 launched with a satire on David Blunkett's private life
Channel 4 launched two pay-channels - Film Four and the youth entertainment channel, E4, which broadcast top American comedies and dramas before they went on Channel 4 itself.
But ITV Digital went bust, losing a billion pounds, and heavy losses prompted Channel 4 to rethink its digital expansion plans.
Freeview replaced ITV Digital, offering no fewer than eight TV channels from the BBC, including BBC Three, BBC Four, CBBC and CBeebies.
It soon demonstrated that many viewers who had previously rejected multichannel television were keen to have extra channels, provided they didn't have to pay a subscription.
But the BBC did face criticism in some quarters for investing in "niche" channels, like BBC Three and Four, which have relatively low audience figures.
Now all the major broadcasters are launching "families" of channels, and more viewers are cottoning on to the fact that there is now a much greater choice with no need for a subscription.
ITV is enjoying great success with ITV2, aimed primarily at young women, and ITV3, which shows dramas from the ITV archive. They're attracting a growing share of the audience, replacing the viewers who are leaving ITV1.
Now it's launching ITV4, aimed primarily at "a discerning male audience", with a mix of blockbuster films, new American comedies and dramas, and top football and boxing. Soon it will launch an ITV Kids channel.
Earlier this year, Channel 4 turned E4 into a free-to-air channel, putting it onto Freeview.
The third series of US drama 24 will be shown on Sky Three
It also revamped its plans for More4, increasing its budget and investing in new drama, comedy and documentaries, to show alongside the repeats it had originally intended to show on the channel. It's now the home of the new series of The West Wing.
Sky, which has seen its flagship channel Sky One lose viewers to ITV2 and ITV3, is now embracing the same strategy.
Sky Three has been launched not just on the Sky platform but on Freeview, in place of the Sky Travel channel.
As well as travel programmes, it's showing dramas and documentaries that have already been seen on Sky One, such as the Kiefer Sutherland drama series 24.
Sky Three has had a very low-key launch - hardly even mentioned on the Sky website.
By contrast, the launch of ITV4 is being trumpeted with press adverts and More4 has been promoted very heavily - demonstrating the importance of marketing in the highly competitive world of the new TV channels.
More4 grabbed attention with its porn-oriented pre-launch advertising, proclaiming it as an "adult entertainment" channel.
But where More4 and ITV4 have really scored in publicity terms is in the cross-promotion they receive on their parent channels - just as BBC Three and BBC Four are promoted on BBC One and Two and on BBC radio and online.
As the major terrestrial channels see their audience share eroded by the multichannel competition, they are hoping to hold on to as many viewers as possible in their new "families" of digital channels.