About a year ago I clicked a Imageshack link in the UI forums to checkout someones UI picture. It gave me a very nasty virus that basically destroyed my computer. The issue was partly my fault for having a very bad anti-virus program at the time. However I have known many people who have reported virus activity through Imageshack.
I would urge people not to use that site and post pictures by uploading them to tankspot directly and then posting them that way. I would also recommend that people not click Imageshack links that take them out of tankspot.
Tankspot I feel is safe, Imageshack IMO is not.
There is something so appealing about backhanding someone across the face with a shield.