Fony is a free bitmap font editor developed by hukka and released for Windows in 2008. It supports several old bitmap font formats. It can open, modify, and save Microsoft bitmaps fonts (FON, FNT), Amiga bitmap fonts, Bitmap Distribution Fonts (BDF), and Bitmap Font Writer fonts. It can also import bitmaps fonts from True Type Fonts (TTF), and bitmaps and export to bitmaps.
The program hasn't been updated in awhile, but the latest version is a pretty great bitmap font editor.
This is the last stable version.