I am primarily interested in high performance computing.
Lately I have been learning how to program GPUs and working on tools for studying similarities between the genomes of different species using bioperl to analyze BLAST results.
I also spend a fair amount of time benchmarking and comparing different HPC architectures and software packages (FFTs, astrophysics codes) when I can't find the information online.
I continue to support an N-Body gravitational code that I helped develop, which has been used to run N=2.90e+10 simulations of cosmic gravitational dark matter evolution, scaling to over 4,096 CPUs (tested out to 22k). You can read more about that work in this Simulating Cosmic Reionization TeraGrid 2008 Conference Science Paper Presentation.
If you're interested in FPGAs you might want to check out my Primer on Mitrion-C and developing for the RC 100