Flickr for Photos
I have used Gallery for hosting my photos on urlgrey.net in the past. However, it was a bit cumbersome to work with and didn't provide any interactive features for the rest of my website.
Enter Flickr, a wonderful, free (or subscription if you want more bandwidth) site for posting, commenting on, browsing, tagging and organizing photos. It has an enormous range of features that are unlike anything I've seen on any other commercial photo site.
I've included a Flickr photo bar on the side of my blog illustrating my most recent photos. This is something I could never have achieved with Gallery. But it only took a couple minutes with Flickr.
I highly recommend that anyone looking to post photos on the web consider using Flickr. And pay for the service, if you can. They certainly deserve it, in my opinion.