Cristina Cifuentes' Homepage. Cristina has done much research into decompilation and program translation. For those interested in decompilation, her Phd. thesis on the dcc decompiler is compulsory reading.
Georgia Tech's Reverse Engineering Group. A good collection of papers, tools and links.
Program Understanding Tools Directory. Useful tools repository. Currently does not contain many tools but hopefully it will be updated.
Honeynet Reverse Challenge. A collection of case studies into the reverse engineering of a piece of malware. Worth reading to see different approaches to tackling the challenge.
REC - Reverse Engineering Compiler. Home of the only publically available working decompiler for the C language.
The Linux Bar (forum). A low volume forum for those interesting in Reverse Engineering under Linux.
Introduction to Reverse Engineering Software. An introduction to Reverse Engineering with a focus on decompilation.