I'm always on the lookout for for fonts that can usefully be used for body text in order to set designs apart from the usual duopoly of Arial and Verdana. As good as those two fonts are, they do tend to make sites look rather generic.
I'm currently working on a small site design and was looking for a font that read well on desktop and phone - surprisingly difficult. I have been using Droid Sans for a while, which does work well but is a little limited in the range of styles (only regular and bold).
My new favourite for body text is Open Sans - available from Google Web Fonts (yes, that means it's free). It is a very versatile font and best of all, it comes in a range of 5 different weights plus italic variants and a condensed version. It is designed by Steve Matteson, who also designed the Droid fonts.
I am using Open Sans in combination with the serifed Cambo font for headings - a combination that seems to work very well. See example below: