Search tools:
www.searchtempest.com Multi-city Craigslist, eBay search
www.adhuntr.com Multi-city Craigslist search
http://archive.org The Internet Archive (aka Wayback Machine)
Training:
LEOTTA (Law Enforcement Officer Technology Training Associates)
Open Source Intel (OSINT) Resources:
http://www.siuhelp.com/ (SIU Help)
http://inteltechniques.com/links.html