Galerie, my favorite iPhoto addition
When my wife came back from New York she wanted to put a big photo gallery online of her trip, but she didn't want to put it on our .mac account. She also didn't want to use the "canned" templates within iPhoto. So I pulled out one of my favorite Mac apps ever, Galerie. It's a totally simple, completely free, solid app for building photo galleries from iPhoto albums. It uses CSS to build the galleries too, which is a plus.
Actually Galerie works with more than iPhoto. Pretty much any set of pictures, audio, or even movies is fair game. It includes a comment system and counter, plus a pretty good collection of additional themes. There are lots of other features, like EXIF support, but just try using it and you'll see what I mean. Very snazzy.