As mentioned earlier, there is a whole breed of viruses being created every single day. However, this is a list of certain viruses that you can be cautious of.
Trojan.MeSpam: This particular virus can spread via IM like AOL Instant Messenger, Yahoo messenger, and Google Talk and also through emails by the various webmail providers like Yahoo, Hotmail, Gmail, and AOL.
Rinbot Worm: This particular virus has a number of variants. Some have known to be in the form of Trojan infecting along with Kelvir.B worm, while others do not need any help from the other viruses and can effectively infect the hard disk on their own.
Skype Chatosky Worm: Skype is basically a phone service that enables users to call using the Internet. The charges are very less and sometimes one can make calls at no charge at all. It also has an IM feature that can very easily spread the virus.
Qspace Javascript Worm: Those who are using MySpace are at a risk of getting their hard disk affected with this virus.
Rontokbro / Brontok Worm: This is a worm that spreads through mass mailing, thumb drives, and USB. There have been more than twenty variants of this worm, which was first discovered in September 2005. These worms have known to disguise as a folder icon or then a Microsoft Word icon. This particular worm can also copy itself and hence leave a trail if not cleared properly.