Try
this one. It's just like Imageshack, but you can upload everything just like that, up to max. 1GB. The files are deleted after 25 days of no downloading (inactive) them, though, so there have to be people downloading them from time to time.
With occasional uploading without account - good for big, complete ISO's but bad for ISO's split into many small parts, as each uploaded file is assigned it's own link. Never registered there so can't say that much about the account options, but if you sign up for a free account the files are deleted only after 45 days of no downloading them. Files with premium account are of course never deleted, but you have to pay monthly.