Wikipedia
Simply the best collaborative information portal out there.
URL: www.wikipedia.org
Ubuntu Forums
One of the best Internet communities helping Linux users figure out common and not-so-common Ubuntu issues.
URL: www.ubuntuforums.org
Google Maps
Simply the cleanest, best, and most useful web application out there. Much, much better than Mapquest or Yahoo! Maps . I love the use of AJAX to make the maps scrollable client-side.
URL: maps.google.com
Craigslist
For obvious reasons, the greatest clearinghouse of things, extra stuff, housing, thoughts, rants, raves, and ideas. I sold my car, rented my apartment, found an apartment, sold my guitar, sold my furniture all on Craigslist…for free. Who needs EBay ?
URL: www.craigslist.org
Froogle
Another winner by Google. Anything you want to buy, start here.
URL: www.froogle.com
Epinions
Before you buy anything, find out how other people rated the product or service.
URL: www.epinions.com