I monitor web surfing habits for one of my clients using ISA Server. Its easy to generate a list by user of their top sites visited. It doesnt matter if its work related but if you are going online to your bank, shopping (ebay etc) or general sites that in no way contribute to the benefit of the company then you will get pegged depending on the company's desire and policies.

Pr0n is a definate immediate termination. Sites like this one are ok if your in the industry and are using it to research some problem in yur program/project but posting away to help everyone else would be the employer paying for you to help people outside their company which can get you fired too.

My employer allows and even wants me to post here!