Help us choose the logo for FOSS4G 2011!

As I've mentioned previously, I'm going to be the chair of the FOSS4G 2011 conference in Denver next September, and I wanted to ask for help in choosing our logo. We've been using a cool site called crowdspring, on which people compete to design your logo, with the winner getting a prize. I have been very impressed at the quality of entries. Please take a minute to have a quick look at these entries and vote for the ones you like (you can rate with up to 5 stars), and feel free to add any comments.

Thanks!