When I open Firefox the following pages are all tabbed automatically as my Homepage:
http://news.google.com/nwshp?hl=en&gl=us - Google news. Doesn't produce content, just exposes you to a little of everything. Makes getting different perspectives and sources simple.
www.arcadecontrols.com - Obvious
www.bensbargains.net - Check it every day - usually multiple times per day. Good deals on stuff. It's like FatWallet, but in an easy to digest, easy to use format.
www.xbox-scene.com - Xbox modification bible - all useful info is here. It's the BYOAC of Xbox modification. Good news, great forums if you want to mod.
www.gizmodo.com - The best blog on the internet. It covers gatgets and robots and gizmos and stuff. The guy who writes it is hilarious. And you learn about all kinds of cool, crazy, amazing, zany, retarded, tiny, huge, funny things.
I also check out
www.gamespot.com,
www.rottentomatoes.com,
www.hyperdictionary.com (every word in a definition is a hyperlink to the definition of that word),
www.dexonline.com,
www.imdb.com, and others on a regular basis, but don't have them bookmarked. I sometimes even go to
www.google.com.