I use Imgur, a photo storage site. It's free and it gives you options for sizing photos for different applications. I've used it for quite a few years now and have never had a problem with it.
Before Imgur I used Photobucket which also claimed to be a free photo hosting sight. After a few years they decided to charge without letting me remove my photos. I lost over 100 pages of photos to Photobucket, many of which were bow building related pics, some were build alongs.