I edit photographs on my computer quite often and use both Photoshop and Corel Paint Shop Pro. However, for cropping pictures to upload to the forum and to use as avatars I tend to use Irfanview, from this site.

It loads in a fraction of a second and although it can't do advanced things like adding text, as Nemyar and Terina have done, it is easy to use and - importantly - it is free!