References for TCS proof techniques
The Complexity Theory Companion by Hemaspaandra and Ogihara.  It's not exhaustive in terms of techniques (I imagine no such book is), but I think it qualifies as an answer to your question.  Here are the titles of the chapters:


The Self-Reducibility Technique. 
The One-Way Function Technique. 
The Tournament Divide and Conquer Technique. 
The Isolation Technique. 
The Witness Reduction Technique. 
The Polynomial Interpolation Technique. 
The Nonsolvable Group Technique. 
The Random Restriction Technique. 
The Polynomial Technique.