I am searching for a list of fonts I can use in CSS. Since these fonts may be copyrighted, which fonts should I use that are available across Windows (as of XP), Mac OS X and, say, Ubuntu 8.04?
I don't want to rely solely on the newer OSs.
A great bonus would be if the same fonts existed on mobile devices.
The only 100% safe way to declare fonts is to use generics as fall backs.
The generics are:
From the W3C
All five generic font families are defined to exist in all CSS implementations (they need not necessarily map to five distinct actual fonts). User agents should provide reasonable default choices for the generic font families, which express the characteristics of each family as well as possible within the limits allowed by the underlying technology.
Fonts such as Arial and Verdana which many web designers take for granted may not be present on Linux browsers (even firefox on centOS from experience). Apple has most of the Microsoft fonts but there are some which are absent.
CSS allows you to use any fonts installed on the system. font-family allows you to list many fonts. If the parser doesn't find the first one installed on the system, it moves onto the next one. That's why most font-family definitions cascade down to sans-serif or serif. If the browser doesn't have any of your fonts, it uses the default serif, sans-serif, or monospaced font, etc.
If you're a sucker for typography, unfortunately until CSS3 fonts take off you're going to have to live with serving up all the good fonts to your Mac users, since Mac OS X has a far greater selection of great fonts installed than Windows. I get a little depressed when I load up my sites on Windows and I'm greeted with a pile of rigid, aliased fonts.