Mirror, mirror, what's the most spreading virus?
From my statistics on beastie.frontfree.net, the winner is Worm.SomeFool family.
beastie# cat clamd.log | grep FOUND | awk '{print $2;}' | sort | uniq -c | sort -rn
1098 Worm.SomeFool.Gen-2
787 Worm.SomeFool.Gen-1
372 Worm.Gibe.F
59 Worm.Mydoom.F
22 Worm.SCO.A
11 Worm.Bagle.Gen-zippwd
9 Worm.Dumaru.K
2 Worm.Gibe.F.UPX.2
2 Worm.Dumaru.Y.enc
2 Worm.Bagle.Gen-1
1 Worm.Sobig.E
1 Worm.Dumaru.A
1 W98.Hybris.E