For simple image hosting to post into blogs, forums, etc. I'm liking Postimage.org
Postimage.org was founded in 2004 to provide forums with an easy way to upload images for free. Postimage is a very simple, fast, reliable free image host. It's perfect for linking to auctions, message boards, blogs, and other websites. Postimage guarantees maximum uptime and performance so your image will be here whenever you need it. There is no registration or login, all you have to do is submit your picture. With continuous upgrades and dedicated staff Postimage is the #1 solution for Free Image Hosting.
Simple, clean interface with lots of link options, and all it's meant for is a place to store stuff you want to link to. The free version has ads, a 5MB per image limit and '6 months no views' deletion policy. A pro account costs anywhere from $2.95 monthly to 23.40 per year (1.95/month) with monthly, 3 month, 6 month, and yearly contracts, has no ads, 10MB per image limit and no deletion.
Imgur is nice, but it's kinda like Wikipedia or TVTropes; I spent WAAAY too much time there browsing the front page pictures, so now I have it blocked.