http://sixrevisions.com/tools/using-design-tools-to-become-a-one-man-design-team/#more-5147
Data-Gathering Tools
- Google Analytics (it has heat maps as well)
- Crazy Egg
- ClickHeat
- clickdensity
- ClickTale
Design Pattern Libraries
- UI-Patterns.com
- Pattern Tap
- Patternry
- Elements of Design: A Web Design Showcase
- Yahoo! Design Pattern Library
- Interaction Design Pattern Library (Welie.com)
Wireframing and Prototyping
I use Axure.