Font Software:
Adobe Type Manager Light (free)- Mostly for older operating systems without internal support for PostScript Type 1 fonts. Windows and Macintosh versions.
Apple Font Tools - Apple conversion, diagnostic, editors and other font tools.
FontForge (free) - This is a versatile open source font editor. It runs under many UNIX/LINUX like systems. To run inWindows it requires Cygwin (a UNIX like shell for Windows).
FontCreator (commercial) - Font creating/editing software for Windows.
BabelPad (free) - A free Unicode text editor for Windows.
BabelMap (free) - A free Unicode character map tool for Windows.

Font Information:
Comp.fonts FAQ - Frequently asked questions about fonts. A wealth of information here.
TrueType, PostScript Type 1, & OpenType: What’s the Difference? (PDF) - Details about the differences between the main outline font formats.
Adobe Typography resources - Creators of Adobe Type Manager, Photoshop, Illustrator, Acrobat and many other software innovations. They have a large type library. This site has lots of useful font information.
Adobe OpenType Tour - OpenType information and feature tour video.
Adobe OpenType FAQ - Answers to common questions about OpenType fonts.
Microsoft Typography home page - Microsoft typography related information, news, fonts, tools, links, etc.
Apple Typography home page - Apple typography related information, tools, links, etc.
Macintosh character access chart (PDF) - Key sequences used to access characters in a standard Macintosh font.
Windows character access chart (PDF) - Key sequences used to access characters in a standard Windows font.
Unicode Character Code Charts - Unicode Character Code Charts for various scripts.
WhatTheFont Forum - Others help you identify a particular font from an uploaded sample.
Identifont - Identify fonts using search or appearance drill down.

Free Font Sites:
dafont.com
Font Squrrel
1001fonts
1001freefonts
Typoasis
Fontface.com
Filecart
Dr. Berlin's Foreign Font Archive- International fonts.
FREELANG Foreign Font Archive - International fonts.
WAZU JAPAN's Gallery of Unicode Fonts - International fonts.