I spend about 4-5 hours per day...
Initially when I came into this thread I thought it was going to be about how much money I spend a month. Anyways, on the topic of hours per day, way too much time these days as I'm off work. These days I spend around 10-12 hours a day, not constant surfing, but it's in front of me while I do other stuff live watch TV and look for work.
When I'm employed, I'll surf the net maybe 3-4 hours. I don't believe in surfing the web while I am working. No one should be surfing the web on someone elses dime, unless it's actually your job to surf the web.
If there is a job out there to get paid for surfing the web though, sign me up!