There are a ton of neat and nifty places to go on the web, but I'm going to practice some constructive nepotism here and introduce you to some friends.
Fabric Bliss: If you are in the Denver area and into fabric at all, you should really check out this new shop in the Santa Fe Arts District. And I'm not just saying that because the owner is my friend. She stocks vibrant prints that make your fingers itch for the sewing machine, and a bunch of other great supplies and handmade crafts as well.
Craftgossip: I love craftgossip. Not only did they feature one of my tutorials, but they just have a wealth of fun ideas all the time.
Springs: This is my husband Guy's website. It's a charming comic about little robots. Think Peanuts or Calvin and Hobbes but with robots making science jokes. It has nothing to do with sewing, but I encourage you to go look.
I'm still working on this list. If you know a page that should be on it, drop me a line!