I'm on Linux Ubuntu, so as my default font for mostly all online content, I use URW Gothic L at 20pt (I can't read small print without a magnifying glass anymore and this is the clearest font for me to read.) It usually translates as Century Gothic (it's Windows TTF counterpart) or Arial at the reciever's (usually Windows) computer.
Man, Ubuntu rocks. I wish it was as mainstream as Windows and Mac. Have you had any experience with Linux Mint? I've heard it's also good and built on the Ubuntu code.