Have recently been experimenting with different side-loaded fonts. Aside from Gill Sans and Avenir which I already liked a lot, Ubuntu -
http://en.m.wikipedia.org/wiki/Ubuntu_(typeface) - is a really stylish yet readable font. Myriad is also very nice, and Open Sans is great especially at larger sizes
http://en.m.wikipedia.org/wiki/Open_Sans
I seem to have a thing for 'humans sand serif' fonts