Some Agile and Estimation links:


Simplicity--the art of maximizing the amount of work not done--is essential. - Agile Manifesto

The beginning - The Agile Manifesto

Research indicates that the average software project is 45% over budget, delayed by 63% and missing 1/3 of the promised functionality.

Agile development practices can reduce those risks.

An Agile Approach to Estimating and Planning: Chapter 3 - An Agile Approach

The Seven Core Practices of Agile Work

Scrum (development)

DRUPALCON ESTIMATING REQUIREMENTS
As part of my session A Method for Getting Early Estimates Right at DrupalCon CPH, I’ve made the example requirements and the resulting estimation sheet available.

Resources for my DrupalCon CPH session on early estimating - JAKOB PERSSON