I have always liked Flickr, but their Flash slideshow is a little lacking. If you have a high-res monitor, then the slideshow on Flickr is really small looking. But PicasaWeb (Google’s Flickr competitor) scales to the size of the browser, and unlike Webshots it actually looks good with scaling.
Example Screenshots:
View example:http://picasaweb.google.com/keithlam/DukePhotos
Notice how it fills the browser window.
Notice how there are many ads, and the scaling is jaggy around curves. Look at the hood of the jacket on the right.
Good navigation, speedy, but the image is the smallest of the 3.