My “best of the web” intentionally kept brief (and a work in progress). You can read all of this in an afternoon. If you’ve got a lot more time, see Dr. John.
Requirements Managment

• Writing User Stories, by Mike Cohn
• Simple Functional Specifications, by Joel Spolsky

Project Management

• Mistakes PMs Make, by Scott Berkun
• Painless Software Scheduling, by Joel Spolsky
• Stand Up Meetings, by Ron Jeffries

Design and Usability

• Design for Programmers, by Joel Spolsky (every programmer on your team should read this)