There is quite a bounty of JPL goodness and all things sciencey on iTunes these days if you search the podcast directory! Stumbled across this while searching for space related podcasts -
Riding With Robots Podcast
It's all stuff we have seen before, but it's sometimes nice to see what another "enthusiast" considers the best of 2006....
The site itself has other goodies for download, including a Widget that displays a pic of the day and a screensaver.