I used to maintain several KDE projects, including Extra CMake Modules project, but have taken a step back recently for personal reasons.
I am one of the lead maintainers of the Media Player Remote Interfacing Specification, a standardised D-Bus interface for media players.

I was also previously involved in a couple of open source projects related to my research:

A tool for doing semi-automated reasoning in graphical languages (see my academia page). Currently, it is mostly just a graph-rewriting tool, albeit with some interesting features for representing a graph with “any number” of copies of a subgraph (!-boxes), but there are grander plans for it.
A graph-editing tool for making the sort of diagrams I used all the time in the course of my DPhil, and generating the TikZ code necessary to put it in a LaTeX document. It is actually possible to use it to make more general diagrams – commuting diagrams from category theory, for example.

In my day job, I work in C++/Boost on software for single-molecule sequencing devices (eg: DNA sequencing).

For my other assorted bits and pieces, you can find me on: