Estimation related stuff (books, tools, etc) that we have found useful:

• Preliminary guidelines for software estimation (Link not currently supported.)
• Software Estimation: Demystifying the Black Art (Best Practices) by Steve McConnell
• Agile Estimating and Planning by Mike Cohn
• The BEST library of estimation papers
• Forecasting Principles
• Paul Coomb’s book on IT project estimation
• Online Planning Poker
• Software Metrics: Measurement for Software Process Improvement by Barbara Kitchenham
• The COCOMO homepage
• International Software Benchmarking Standards Group, Data Repository (historical data)