Cantarell is a GNU licensed font family designed by Dave Crossland. He was part of the 2009 class in the Department of Typography at the University of Reading (UK). The font is specifically designed for easy reading on small-screen devices like the iPhone, G1 and Palm Pre.
I think it reads very nicely and admire his unique approach in releasing the font under a public license. At his site you can find Cantarell available in TTF and EOT formats, so you should be able to find a way to embed it in your web pages and have it render across most modern browsers – even IE7!
You can view additional fonts from the 2009 class at typefacedesign.org.
Chatter