Microsoft Typography: OpenType and TrueType specifications, free tools (Microsoft VTT, Microsoft VOLT, Microsoft Font Validator, CacheTT and other tools), various technical articles and recommendations.

Adobe Developer Type Technology: OpenType and Type 1 specifications, free tools (Adobe FDK for OpenType), technical articles.

Apple Font Site: TrueType specification, free tools (Apple Font Tools), technical documents.

FontTools/TTX: free tools to convert OpenType/TrueType fonts to XML and back.

Robofab: free Python tools that extend FontLab's capabilities

More links are available at MyFonts.

Text FAQ (zipped)

PDF FAQ

Finding Fonts for Internationalization FAQ