There are so many people with pickpocket stories to share. Also many of them share their best tips on how to avoid getting in their situation. Of course there re also official tourism pages with travel recommendations and there are the traditional media pitching n. Below are some links to what I found most useful.
10 worst cities for pickpockets is a list by the Huffington Post travel.
The UK Police has some excellent travel tips and information. Surprisingly, they say that women account for 80% of pick pocket victims.
BarcelonaYellow's title says it all 'Spot the tourist'. Yes it really is as easy as that for pickpockets.
Pickpocket blog is a blog about...pickpockets.
Travel Rants has named the worst cities for pickpockets.
How stuff works explains how pick pockets actually do what they do.
Lonely Planet's forum is excellent for place specific advice such as this discussion on how to travel on the ferry to Pelni.
Tripadvisor is also useful for all things travel and safety too.
And finally the newcomer Gogobot, which si more of a recommendation site, but still useful.