A collection of software I've written, all useful to a greater or lesser degree.

dlr:
a command-line Flickr downloading tool; think backups of specific sets.

dailyphoto:
a PHP-based webapp for uploading and displaying dailyphoto diptyches for collaborating photographers.
Very alpha, and site-specific for ciaron.net/dailyphoto, but it might be useful for someone.
I learned a lot on this project: PHP, MySQL, Javascript, AJAX with Dojo.

findonflickr at github:
a Nautilus plugin/extension for finding the photopage for downloaded Flickr images with filenames of the form "12345678_fds432_o.jpg"