@baldur btb: Ubuntu is a rather horrible font, compared to Dejavu Sans, Droid Sans and even parts of Open Sans. The aforementioned fonts are also major linux system fonts, and I'd rather see them everywhere (preferable the first two) than the Ubuntu system font. They say it's a relative of Futura and Helvetica Neue, but it still got some waay too ugly edges .. Droid and Dejavu Sans are much more precise and refined, compared to that. /1
@baldur Most of my sites, esp. AlltagsGrauen.info and Usability-Idealist.de, are based on the aforementioned sans serif system fonts, plus a serif type for headlines. So far, no other serif web font could keep up with the roundish, turning clunky into something elegant and refined style of the numbers and upper case alphabet of Georgia, thus its my main and usually system font for said headlines.