www.digg.com

i spend hours on it digg, some really cool info is out there....
also
www.i-am-bored.com

and then i go to www.wikipedia.org ad start researching stuff i am interested in (soccer teams, history of soccer teams, countries, people etc)

also youtube is gr8 for killing time, and www.thatvideosite.com is a similar youtube

there is also break.com

the above should guarantee you a god 5 hours of fun surfing..