Photo Gallery Generator is a compact (403KB download) portable tool which aims to help you create HTML thumbnail galleries from your favourite photos.
The program has an unusual interface which may leave you confused, at least initially. There are no menus to explore, there's no wizard to walk you through the slideshow creation process. Instead there are just lots of small buttons scattered around the main application window. It's not always clear what these do, either, although they do at least have tooltips to help you figure things out.
The non-standard approach continues when you're choosing which images you'd like in your photo gallery. For some reason Photo Gallery Generator ignores the standard Windows file selection in favour of its own. Which might make sense if it were better, but in fact it's significantly worse: it's horribly slow to load, and appears to display images in 256 colours only.
Still, once you've figured how the program works then life does improve, and you'll be able to import images, set descriptions and generate capable web galleries in just a few minutes (see an example on the Photo Gallery Generator site).