The <a href="http://sat.isa.ru/pdsat" rel="nofollow">SAT@home project</a>, from the Institute for Systems Analysis of Russian Academy of Sciences, solves hard and practically important problems (discrete functions inversion problems, discrete optimization, bioinformatics, etc) that can be effectively reduced to the Boolean satisfiability problem.
<img hspace="8" src="http://boinc.berkeley.edu/images/sat_logo.png">