Try Flickr, it is probably the most popular (free) hosting site. I don't really like Flickr and use Photobucket mainly, but I do have a Flickr account. I just get more organization for free through Photobucket. And i don't like that I can't see EXIF info on Flickr photos on the photography forums. Flickr does do a nice quality job of letting you choose a resize for forum posting though. Photobucket will compress horribly if you upload anything larger than 1024x768, which is still too large for forum posts anyways.