Well, let me tell all of you about Liberation fonts. These are, to my eye, very clean, attractive fonts for both screen and print use. Red Hat designed them together with Ascender Corp., a leading commercial developer of fonts, to develop font sets that were metrically equivalent to the major Microsoft fonts.
Red Hat and Ascender were successful. There are three sets of Liberation fonts: Sans (a substitute for Arial, Albany, Helvetica, Nimbus Sans L, and Bitstream Vera Sans), Serif (a substitute for Times New Roman, Thorndale, Nimbus Roman, and Bitstream Vera Serif) and Mono (a substitute for Courier New, Cumberland, Courier, Nimbus Mono L, and Bitstream Vera Sans Mono). Specifically, Sans is closest to Arial; Serif works best as a replacement for Times New Roman; and Mono is a near-twin to Courier New.
These fonts are licensed under the GPL+font exception. What that means is that you can use them in any document on essentially any desktop operating system without having your document fall under the GPL or any other licensing requirements.
The Liberation fonts, which are currently at version 1.04, can be used for all purposes. They now come with full hinting capability. Hinting adjusts font pixelization so that the fonts render with high quality at both large and small sizes. In short, whether you're just reading friends' Twitters or publishing a book, Liberation will work well for you.
Most, but not all, Linux distributions now come with Liberation fonts. To see if you already have them, just use your usual package manager, such as OpenSUSE's YaST; Debian/Ubuntu's Synaptic; or Fedora's PackageKit manager, to see if they're installed. If they're not, just grab them and let the package manager install them for you.
If you need to install these fonts manually, the instructions in this Linux Journal article are still good. For the BSD Unixes, the FreeBSD Handbook will give you the guidance you need. Finally, for Solaris and OpenSolaris, you can just follow the instruction in the section labeled "Adding Fonts to Your Account" in Adding True Type Fonts to Solaris.
Once the fonts are in place, you can choose to use them in your desktop environment or program using its usual font selection tools. Personally, I'm fondest of Liberation Serif, but regardless of which one you pick, I know you'll find that this trio of fonts makes all your computer uses easier on your eyes.