Smallpot: Tracking the Slapper and Scalper Unix Worms
It all begun with the Ramen worm, then continued with Adore, Lion, Cheese, RST.B and many, many more. Some of them even became widespread, culminating with the inclusion of OSF.8759 in the May 2002 Wildlist
Unfortunately, while there are lots of charts and distribution statistics available for Win32 viruses, the same cannot be said about Unix viruses. Actually, at the time of writing, there is no reliable (and constantly updated) source of information regarding the distribution of Linux/FreeBSD malware, not to mention other Unix flavors which are less appealing to virus writers.
The link for this article located at SecurityFocus is no longer available.