Fonts:

• The LaTeX Font Catalogue
  is aimed to display and explain all free fonts available for use with LaTeX
• LaTeX Font Sampler
  lists LaTeX fonts coming with TeXlive
• A Survey of Free Math Fonts for TeX and LaTeX
• Font Installation Guide
  discusses the installation of Type 1 Postscript fonts
• TeX Font Guide
  handling of fonts in a TeX system
• Fonts and TeX on tug.org

Symbols:

• The Comprehensive LaTeX Symbol List
  lists nearly 5000 symbols and the corresponding LaTeX commands that produce them
• Compact lists of symbols
  simpler list as beamer class presentation