One of the other new things I'm doing now that I'm running my website with PHP is implementing an all-new art gallery system. As much as I liked Picassa, the new PHP-based SPGM tool that I'm using is much more flexible (if you have prior programming knowledge). I've had to make a number of extensions and changes to SPGM to make it work the way I want, but I think the result is very nice. The new gallery system allows me to do hit tracking on the image pages, add comments to individual images, and more. Before I had no idea if anyone was even going into my gallery at all, or how much anyone looked at. It's also really nice to be able to add little explanations or background notes to each image.
Also nice is the ability to have albums within albums. Many of my albums now have sub-albums that have the lesser-quality images available, but less prominent. This is helpful because there are some legitimately interesting images that fall under that category, but I want to have only my better work showing in the main galleries.