At the time of writing, my personal website uses the typeface Source Sans Pro and has done for around two years. I already employ a number of its cool features however this lovely demo page provides further inspiration.
Source Sans Pro is a versatile typeface designed particularly for user interfaces. Its letterforms are slightly condensed allowing them to fit into tight spaces within a UI, and remain well-defined even at small sizes.
I might consider going back to using Source Serif Pro for headings again, too.