Linux Font Equivalents to Popular Web Typefaces

Very useful article:

I have written before about my admiration for Web typography, and in that article I touched on the fact that many “Web safe” fonts can’t be applied to Linux. Linux distributions each ship with their own font libraries, but I’d like to focus on similar typefaces you can use within a font-family to help make your design bulletproof.
Like Windows & OS X, Linux does type too

I’ve been a Linux user for some time now, and Linux is my platform of choice both at work and at home. My distribution of choice is Ubuntu not because it’s the most popular, but because I’ve tried a wide variety of Linux versions, and Ubuntu works the best for me. I say this because I’m going to focus on the fonts that ship by default with Ubuntu, so there may be some discrepancy among distributions.

more here