[Rich] over at Securosis takes us through some of his browser paranoia exercises. He uses different browser profiles for different types of web activities. Based on potential risk, various tasks are separated to protect from CSRF attacks and more. Everyday browsing with low risk passwords is done in one. RSS reading with no passwords is done in another. He runs his personal blog in a browser dedicated just to that.
For high risk research, he uses virtual machines to further minimize any potential nasty code getting through. Very high risk sites are browsed through a non-persistent read-only Linux virtual machine. While these techniques can be less effective if the entire OS is comprised, they can still provide a few layers of additional security.