TypeTool is a basic font editor for small font manipulation jobs. It can import and export TrueType, Type 1, and OpenType (TT-based) fonts. It has extensive glyph drawing and editing tools and manual and automatic kerning capabilities. Autohinting is also included. TypeTool supports virtually all font encodings and codepages and can import/export fonts with up to 64000 characters.
Version 3 features: precise glyph measurement with the Meter mode ruler; true support for open contours and Fontographer-compatible tangent points.
Type Tool is a nice small app with a clean interface with all the editing features it should have. If you're comfortable editing vector graphics in Illustrator, Flash or what have you, then you'll have no trouble getting use to Type Tool 2.