I’ve created a new figured bass font which may be downloaded via the Free Fonts section of this website.
It is a simple yet powerful font that has the facility for four rows of figured bass, plus the relevant accidentals and slashes.
This font was designed for use with the Finale application as well as Microsoft Word. Sibelius users already have a great figured bass facility within that application, so they will have no need for this font (most likely).
This font was designed for use primarily on a Mac. It should work fine on a PC, though I’ve yet to test it.
If you require a more powerful font, then there are few alternatives: namely, the Caltabiano Siciliano font and Ansgar Krause’s font. There is also a freeware figured bass font available from: http://www.lombardi.ws/musicFont/ - this font is great on the PC but lacking easy-to-use keystrokes for the Mac.