Imgur is excellent! I use it for most things, generally graphics (sigs, avatars, ponysona refs, etc). I prefer Flickr for photos but that's mostly because of how many I take/upload. I keep all of my uploads private on both sites and haven't had any issues at all.
I recommend avoiding Tinypic because they reuse URLs so your innocent pony picture could be changed to a NSFW photo. Its happened to me before ):
I recommend avoiding Tinypic because they reuse URLs so your innocent pony picture could be changed to a NSFW photo. Its happened to me before ):
Seconding this - I've seen this happen and I've also seen them just remove images at random, no warning, and replace them with a "image not found" image. Definitely stay away from Tinypic :(