I have just started this blog so the list is not very long yet :), but there is still a nice amount of free image host sites. Many people need image hosting for things like forums, ebay or blogs and this is the place to find the best ones out there!
No Sign-up Required
http://www.Imageshack.us
http://www.Imagewaiter.com
http://www.Imagetown.net
http://www.Picrack.com
http://www.Imageupload.com
Requiring Sign-up
http://www.Photobucket.com
http://www.Walagata.com
http://www.250Free.com
http://www.UploadIt.org
http://www.Miamihost.net
No Sign-up Required
http://www.Imageshack.us
http://www.Imagewaiter.com
http://www.Imagetown.net
http://www.Picrack.com
http://www.Imageupload.com
Requiring Sign-up
http://www.Photobucket.com
http://www.Walagata.com
http://www.250Free.com
http://www.UploadIt.org
http://www.Miamihost.net