This article provides a great overview of a lot of insights and lessons from studies about pricing over the last few decades. It covers a number of approaches:
- Decoy pricing
- The magic of number 9
- Anchoring and the contrast principle
- Straightforward pricing
- Pay what you wish
- Offering 3 options
- Price perceptions
- How to split test prices
Each point is covered in enough depth to be useful (this is not one of those "7 ways to tweak your pricing" articles that provide nothing useful. Have a read, and you'll probably learn something.