Flickr is nice, but such a long walk through the park to get the right link to share.
Photobucket can be nice, but so spammy with all the ads and other things if you're not paying for it.
ImageShack *was* a very nice alternative but went completely Pro.
I also use, occasionally use:
http://postimg.org/
https://someimage.com/
And there was another decent one... orange icons...orange theme...or was it yellow... :erm: