I derived from Picasa and tried Photobucket. The main reason for the test is the limitation of Picasa with direct links: the pictures are quite limited in size. Photobucket offers larger directly linkable images. But they have a lot of advertisement and the user interface is somewhat confusing. Their picture uploader is a Java app - so it runs from within the browser which actually works quite well. I'll embed a Photobucket slideshow below.