min.us
This is pretty excellent. As an alternative url if min.us is blocked, try minus.fm.

http://imgur.com/
Note that this will convert large files to jpegs, so no huge spritesheets.
Smaller sprites or other images which won't suffer from compression are fine.

http://filesmelt.com/simple
Files! This is super simple, and also lets you upload multiple files at once should you want to.
Large spritesheets can go here without any problems if imgur compresses them.

Technically you could just use filesmelt for everything, but as I just do images most of the time, I stick with imgur for the most part.

http://Imageshack.us and http://Cubeupload.com are also viable options.

Dropbox is very good too.

imageshack is the best image host. filesmelt is blocked by multiple work-network filters for various reasons, making it pretty terrible.

imgur converting barely big images to jpegs is terrible.

imageshack won't rape your images!!!

Plus it saves your images for pretty much forever.

tinypic is also reliable.
It keeps a history on what exactly you uploaded.

Fair enough, cheers for mentioning that.

Imageshack uploads succeed sporadically at best for me, hence my preference of imgur for most things.
I dislike tinypic because you either have to sign in or do a captcha which is annoying.

Dropbox is pretty good, especially for stuff you're going to make changes to.

Cubeupload is... pretty good actually. 5mb size limit is potentially annoying, but fine for images.

Edit:
Wow. min.us seems pretty good. Fast uploads, no compression, no login. I can endorse this ♥♥♥♥.

It's less important what host your choose and more that you save copies of what you want to upload as a .png if it's spritework to keep the filesize down. Imgur has never converted my images to .jpg from .png.

I've heard imageshack converts .bmp automatically to .jpg, and don't blame them, though you'd think they'd opt for .png instead <_<

Imgur only does that with fairly big images, I think, though I've never bothered looking at it closely.

Hi!

John here from Minus ( http://min.us )
Thanks for sharing Minus, really appreciate it! Hope you can continue to help us spread the word

Cheers

Well, I think Minus seems to be one of the most simplified sharing sites I've ever seen.
Good one.

minus is really nice. the only worries about it I have is its chance to vaporize off the face of the earth as sites such as this tend toward.

Hory shet!
I'm officially in love with min.us
It's bloody great!

Yeah it's pretty darn awesome allright.

Too bad I chose ImageCave, since I don't want to take sides on the photobucket-imageshack conflict.



CAVED!!!