intelligence gathering

Not too long ago I was at a local Borders bookstore and had an urge to read something with a military background. I looked at books on tactics and books of historical value but I finally settled on something relatively current. I settled on the ARMY/Marines Counterinsurgency Field Manual. This book is of particular relevance to incident response and even forensics given the underground communities that often are encountered. I've taken a number of pages and dog-eared them and highlighted several sections so far. Perhaps one of the more interesting subjects is that of intelligence gathering. Intel gathering in COIN operations largely involves getting out and dealing with the population, earning their trust and respect and protecting them.

Since I'm just your average citizen - that is I don't walk around with a badge and gun, and I don't arrive in a black helicopter..I have the advantage of scoping out what's happening without drawing attention, which is to say I can shoulder surf much easier than some. I was at a public library recently picking up a book and as I was walking back to the circulation desk I passed through the public computing zone. There are common sayings in our society where advice is often given. I'd like to add a saying.. "If you want to gather intelligence on what software people may be using to conduct suspicious activities, shoulder surf at a public computing zone". I now a have a list of software to take a look at as a result.

Here's just a few applications I saw in use:

Idrive
wixi
meebo

Have you seen any interesting applications in use by people? Either during a case or during intel gathering? What are your favorite spots to gather intel?