I had pre-registered for Stardust@Home a while back and had forgotten all 
about it until receiving an email today.  Its based around that probe that 
returned to Earth comet particles from Wild2 a while back.

This is a different type of project in that there is nothing to download for 
Boinc.  Its not "distributed computing", but rather "distributed human 
work".   There are no "work units" to be crunched, but rather "focus movies" 
that run inside a "virtual microscope" in your web browser.  Its pretty 
neat, allows you to change the focus around like an actual microscope.  They 
give you a tutorial of how and what to look for -- and a test at the end. 
They have 1.6 million of these "focus movies" that need eyeballs to go over 
them.

Incentives are you get to give a common name for any comet particle you 
find, top discoverers get a field trip to their actual labs, but perhaps the 
best incentive is that you can pretend you are a "real scientist" -- and it 
doesn't require a computer farm in the basement.

http://stardustathome.ssl.berkeley.edu