Photobucket is also free. I know they limit the amount of photos you can upload but since it's my back-up photo storage location I don't use it very often.

This comes from the Photobucket website:


Free accounts include:
  • Unlimited* storage for photos.
  • Up to 500 videos permitted with up to 10 minutes in length per video.
  • Maximum display size of photos is 2048x1536 pixels each.
  • Maximum file size permitted is 5MB per photo and 500MB per video.
  • The pure awesomeness of the Photobucket experience!
*Photobucket reserves the right to limit excessive use and the unlimited storage offer pertains to non-commercial use only.