PyAddfiles - A utility to create HTML slide shows from your holiday photos, written in Python.
This is free and unencumbered software released into the public domain. http://unlicense.org/
You create groups, add some photos to each group and then click the "Generate HTML" option. It will generate an index.html page containing the chosen thumbnail for each group, and when you click on the thumbnail you can browse the photos in each group.
There are some additional operations, like scaling your photos to fit on your screen and rotate them.
In order to use this application, you need to have Tkinter (the Python Tk bindings) and the Python Imaging Library (ImageTk) installed. On my Linux Mint machine it was as simple as typing:
$ sudo apt-get install python-tk python-imaging-tk
See the file help.txt for a user guide.