If you have graphic design experience, check out the on-going logo design competition at 99designs for the Singularity Institute. There are still 6 days left to enter and be eligible to win the $295 prize if your design is selected. Tell your friends with graphic design experience too. There are very few submissions currently.
Note: This is a blind contest. Designers can only see their own entries. All designs will be revealed when the contest ends.
If you're interested at getting a peek at the designs, they will be online after the competition is over. This is standard practice in 99designs contests to prevent designers from contaminating each other and having all the designs drift in a certain direction.
Insider info: This was tried. There have been e-mails going around with many many logos by a hired artist attached to them. There is approximately zero consensus and most people aren't happy with any of the logos.
I for one would get some utility from any further information about what sorts of designs were rejected and why. I've been working on SI logos for much of the last two days, but have no way to guess if I'm on the right track (other than that I like them, of course).