Post your favorite website, other than Pixies. This is a site that you visit and USE every day.

RULES

No affiliate links. No link that you or someone else will gain from being visiting. No stores. No auctions.
List USEFUL resources that you want others to know about.
If this thread gets full of junk, I'm sure the moderators will delete it. So, keep it cool, and let's share some information.

Just list one per response, and tell why you like it. You can always post another favorite later.