We use Arial a lot, for it's readability. However, Verdana and Tahoma has the ability of being extremely small, yet still readable, thus making it a more recent choice of our's.
Only if we really need to, we use specialized symbol or special stylized fonts from our font library.
I am of course referring to actual font text, not text in images.
When it comes to images.....anything goes as far as font is concerned.