To get things started, here are some very useful links for programming language theory:

• Lambda the Ultimate -- Excellent weblog for PL theory
• Frank Atanassow's PLT Online -- Huge collection of useful links
• Library of Scheme-related Research
• Online Bibliography of Haskell Research
• Daniel Bonniot's Nice-related papers -- Kinds, ML-sub type systems, and more.
• Concepts, Techniques, and Models of Computer Programming -- Great book for understanding computer science. Like SICP, but up to date.