Brain Malow of sciencecomedian.com likes to tell science jokes. He was seen on Fora.tv as part of Wonderfest 2009. He’s on YouTube here, here, here, and on the Late Show with Craig Ferguson.
Another science comedian is Norm Goldbaltt as seen on fora.tv.
Tim Lee is a scientist who became a comedian and will actually sometimes use Powerpoint in his comedy as seen here and here.