Maybe this isn't as much fun as goofing around on websites, but my first suggestion would be to look around and find more work that needs to be done. Bosses love initiative, and people that figure out what can be done to make something better, and just DO it. Find a need, and fill it. Become the "go-to" person in the office. Does everybody else there have as much free time as you? If not, maybe help them out.