Lumunon Media is providing unlimited image hosting (without account creation requirement) which you can use for posting images on message boards, blogs, online auctions, classifieds and even sharing pictures with your family etc.

There are two catches. First each image size has to be less than 500K. Secondly the image is guaranteed to be kept for at least 60 days. They may delete it after that at their discretion. However as a workaround they suggest re-uploading the image.

They support gif, jpg/jpeg, png formats. As usual they will host any image to which you have the legal rights to use, except for adult or pornographic images.

Website

For Bloggers:
I think it will be a good solution for getting some burstable bandwidth for say your slashdotted image. Later on when the surge dies down you can relocate it in your server.

If you are on blogspot then this is a good way to show images in your blog.