Links, useful and otherwise

Useful:
Meetup.com, the self-obviating site.
LinkedIn, for professional networking.
Movie tickets! No lines!
An insanely complete collection of hardware. Stuff made of METAL.
Temperature sensors, controllers, force sensors, the lot. A scientist's bathroom reader.
Order tires and wheels online. It makes more sense than you realize.
A pretty thorough site for researching cars, unfortunately very slow and hard to navigate.
Food! Epicurious covers the magazines Gourmet and Bon Appetit.
More food! We make several recipes out of Cooking Light every month.

Funny:
Toothpaste For Dinner, a minimalist webcomic
Cat And Girl, a webcomic so highbrow that I don't understand it half the time, but when I do, it rocks
XKCD, another minimalist webcomic, human and funny and sometimes serious
Banksy. That graffiti guy.
Electron Band Structure In Germanium, My Ass

Time-killers:
SOMAFM, several great internet radio stations. We're currently partial to Lush and Groove Salad.
Flickr, fun free online photo community
EMusic, a pay-per-download MP3 site
Allmusic, publishers of All Music Guide books, very thorough info
Madisound, in case you ever want to build your own speakers.

All links work as of Q4 2008.