Here is the wikipedia article listing many different viruses.

http://en.wikipedia.org/wiki/List_of_viruses

of particular interest at the moment in the Swine flu A/Veracruz/2009 (H1N1)

http://en.wikipedia.org/wiki/Swine_influenza.

The Big Idea That Might Beat Cancer and Cut Health-Care Costs by 80 Percent Paul Ewald says infections are responsible for at least four-fifths of all cancers—and we have the tools to prevent them.

http://discovermagazine.com/2009/new-science-of-health/big-idea-beat-cancer-cut-health-care-costs-80-percent/

Viral Biofilms

http://www.sciencedaily.com/releases/2010/02/100205115946.htm

sexually transmitted infections

A lot of cancer is probably linked to STI's.

All STI's need to be considered.

for example HIV/AIDs, Herpes Simplex Virus, HPV virus.

HIV

Hepatisis C

Antivirals

Pentagalloylglucose antiviral composition

http://mct.aacrjournals.org/content/8/10/2833.abstract

Can't find much in hubmed about it though.. will need to list a lot more.

Anti Viral Supplements