Links from Matt Might

Learn Perl by experiment
A quick overview of programming with bash
A short introduction to make
SSH hacks
Standalone lexers with lex: synopsis, examples, and pitfalls
Sculpting text with regex, grep, sed and awk
Relational shell programming
Settling into Unix
A survival guide for Unix beginners
Console productivity hack: Exploiting task frequency
HOWTO: Word, Excel and PowerPoint without MS Office
Tips, tricks and tools for Linux and Unix