• Guidelines for typography (Typography Resources)
• TypeNeu - Typography News
• iLT - iLoveTypography
  inspiring articles concerning typography
• JEP - Journal of Electronic Publishing
  research and discussion about contemporary publishing practices
• slanted - German mag, typography and design
• typographica - journal of typography featuring news, observations and
  commentaries on fonts and typographic design
• Planet typography
• All Good Things Typography

In German language:

• typokurz - summary of typographic rules
• typografie.info - portal site with forum and wiki
• typolexikon.de
• Typografie glossar by desig-n.de
• Typographic rules and their implementation in LaTeX