Swimming star Michael Phelps took his gold medal count to six as the USA broke the world record in the men's 4x100m medley relay final.
On the track, Sweden's Carolina Kluft won gold in the heptathlon, and Yuliya Nesterenko won the women's 100m.
Justine Henin-Hardenne won the gold medal in the women's tennis singles.
And Great Britain enjoyed a magnificent day winning five golds, including a thrilling rowing triumph for Matthew Pinsent in the men's coxless fours.
In the pool, Aaron Peirsol led off the US team in the 4x100m medley relay, breaking the world 100m backstroke record in his opening leg.
That set the tone for the remarkable win which earned Phelps' another title even though the teenager did not actually race - he was given gold as he had taken part in the heats.
That gave him a final tally of six golds and two bronzes, meaning Phelps matched Soviet gymnast Alexander Dityatin's 1980 record for the most medals at one Games.
World champion Inge De Bruijn secured her first gold in Athens, outpacing her rivals in the women's 50m freestyle.
Australia's Grant Hackett successfully defended his 1500m title, but there was delight for Britain's David Davies who took a superb bronze in a new European record time.
Australia's women smashed the world record in the 4x100m medley relay, clocking a brilliant three minutes 57.32 seconds to beat the United States.
In the athletics, Swedish star Carolina Kluft took Denise Lewis' place as heptathlon champion, producing a brilliant performance to take gold with 6952 points.
And there was delight for Britain's Kelly Sotherton whose tremendous form over the two days was rewarded with a fine bronze medal, just 11 points behind Lithuania's Austra Skujyte.
The event ended in disappointment for Lewis who pulled out of the competition while languishing in 18th place.
Yuliya Nesterenko of Belarus was celebrating after winning the women's 100m final in 10.93 seconds ahead of Lauryn Williams of the USA and Veronica Campbell of Jamaica.
Mark Lewis-Francis and Jason Gardener both reached the semi-finals of the men's 100m - but the British pair face a tough task to reach the final as five men dipped under 10 seconds in the second round.
But Kelly Holmes was an impressive qualifier for the final of the women's 800m, the British runner clocking the fastest time in the semi-finals.
Natalya Sadova of Russia won the gold medal in the discus with a throw of 67.02
metres, ahead of Anastasia Kelesidou of Greece.
At the tennis arena Belgium's Justine Henin-Hardenne took the women's singles gold medal, beating France's Amelie Mauresmo 6-3 6-3. Unseeded Australian Alicia Molik won bronze.
Argentina's Paola Suarez and Patricia Tarabini of Argentina beat Japan's Shinobu Asagoe and Ai Sugiyama 6-3 6-3 to win the women's doubles bronze.
A busy morning at the rowing lake was capped by Pinsent claiming an historic fourth Olympic gold as his crew pipped world champions Canada in an awesome race in the men's coxless four final.
The four of Pinsent, James Cracknell, Ed Coode and Steve Williams edged out Canada to win by 0.08 seconds in a photo finish.
Cath Bishop and Katherine Grainger, in their last outing together, stole in for silver behind a ruthless Romanian performance in the coxless pairs.
In the double sculls Sarah Winckless and Elise Laverick claimed an impressive bronze.
In sailing, Ben Ainslie won gold for Britain in the Finn class.
Ainslie emulated the achievements of the Yngling crew, who won gold on Thursday, with a composed performance in light winds to hold off the challenge of second-placed Rafael Trujillo of Spain.
But Nick Rogers and Joe Glanfield in the 470s, who had been in pole position for much of the competition, failed to overhaul their American rivals Paul Foerster and Kevin Burnham.
Bradley Wiggins won Great Britain's second cycling gold in the men's four kilometre individual pursuit.
The 23-year-old produced an awesome display to beat Australia's Brad McGee in a time of 4:16.304 seconds.
But there was disappointment for the men's sprint team who were edged out by eventual gold medallists Germany.
Britain's Leslie Law was awarded individual gold in the three-day event after Germany were stripped of their gold medal following an appeal.
The decision also meant Britain's team bronze has been upgraded to silver, and Pippa Funnell takes individual bronze.
The appeal came after the Germans were given first place following their protest against against a 12-point penalty to Bettina Hoy.
France were awarded the team gold medal, with the United States promoted to bronze.
But Germany clinched the team dressage gold medal, their sixth successive Olympic title, thanks to a superb effort by top rider Ulla Salzgeber.
Elsewhere, Lithuania defeated the United States 94-90 in their basketball preliminary round game, only the fourth loss in 115 Olympic starts for the defending champions.
Iraq's amazing Olympics continued when they reached the semi-finals of the men's football after a 1-0 win over Australia.
George Asanidze of Georgia won gold in the men's weightlifting 85kg category, with Greece's triple Olympic champion Pyrros Dimas only able to take bronze.
Taufik Hidayat won Indonesia's first gold medal in the men's badminton, beating seventh-seeded Shon Seung-mo of South