Best Practices for Computer Forensics by the Scientific Working Group on Digital Evidence.

Cell Phone Forensic Tools: An Overview and Analysis by Rick Ayers, Wayne Jansen, Nicolas Cilleros & Ronan Daniellou, National Institute of Standards and Technology,  2005.

Collecting Evidence from a Running Computer:  A Technical and Legal Primer for the Justice Community by Todd G.Shipley and Henry R. Reeve, Esq., The National Consortium for Justice Information and Statistics, 2006.

Creating a Cell Phone Investigation Toolkit:  Basic Hardware and Software Specifications by Keith Daniels and Chris Sanft, The National Consortium for Justice Information and Statistics, 2006.

Creating a Forensic Computer System:  Basic Hardware and Software Specifications by Search Training Services, 2006.

Crime Scene Investigation: A Guide for Law Enforcement by the U.S. Department of Justice.  Not specifically forensic related, but a good idea to review in case you are the first on scene.

Digital Evidence in the Courtroom: A Guide for Law Enforcement and Prosecutors By National Institute of Justice.

Directors and Corporate Advisors' Guide to Digital Investigation and Evidence by the Information Assurance Advisory Council (U.K.), 2005.

Electronic Crime Scene Investigation: A Guide for First Responders by the National Institute of Justice.

Forensic Examination of Digital Evidence: A Guide for Law Enforcement by the National Institute of Justice.

Guidelines on Cell Phone Forensics (Draft) by the National Institute of Standards and Technology.

Guidelines on PDA Forensics by the National Institute of Standards and Technology.

Guide to Integrating Forensic Techniques into Incident Response by the National Institute of Standards and Technology.

Investigations Involving the Internet and Computer Networks By National Institute of Justice.

NIST CFTT: Testing Disk Imaging Tools by James Lyle, National Institute of Standards and Technology.

PDA Forensic Tools: An Overview and Analysis by Rick Ayers & Wayne Jansen, National Institute of Standards and Technology, 2004.

A Road Map for Digital Forensic Research a report from the first Digital Forensic Research Workshop (DFRWS), 2001.

Searching and Seizing Computers and Obtaining Electronic Evidence in Criminal Investigations  Computer Crime and Intellectual Property Section, Criminal Division, United States Departmet of Justice.

Viewing Email Headers by The National Consortium for Justice Information and Statistics National Criminal Justice Computer Laboratory and Training Center.