FontXChange can easily convert fonts to OpenType (PS), PostScript Type 1, and TrueType for both Macintosh or Windows. Useful features include:

Batch processing for converting entire font libraries
Preferences to set font encodings
Font inspection window with preview
Support for many font encodings, including Adobe Standard, Unicode, Mac Roman, and Windows ANSI, and European. 

FontXChange is designed to understand many different font formats and can convert fonts into many different formats. This makes FontXChange useful to:

Convert PostScript Type 1 fonts (Macintosh or Windows format) into a single modern OpenType font file that works on both Macintosh & Windows. End the headaches of the outdated two-file system of screen font and printer font combinations. Just one font file that works.
Recreate missing screen fonts using a PostScript font file in any format.
Convert TrueType fonts to PostScript fonts. No more printing problems and incompatibilities associated with TrueType fonts and high-end output devices.
Convert Windows fonts to Macintosh to Macintosh and vice-versa. Easily share fonts across different computers, even different operating systems. 

What's New
Version 3.1.2: Release notes were unavailable when this listing was updated.

Requirements
PPC / Intel, Mac OS X 10.4 or later. 

Credits to Special [K]