Here's a guide...
http://www.ampsoft.net/webdesign-l/WindowsMacFonts.html
As for mobile, all I can say is good luck! My daughter got my Blackberry from me for five minutes and changed my background, ringtone, and now all my fonts are cartoon fonts.
Here's a list of iPhone fonts, but it maybe slightly out-of-date. http://daringfireball.net/misc/2007/07/iphone-osx-fonts
