The easiest way to track Bitcoin's geographic adoption by location would probably be the interactive merchant map at
http://coinmap.orgIt uses Google Maps as a base so you can pan, zoom, etc.
O man someone beat me to the punch. I was kind of phishing cause I started cryptocoinmaps.com doing something similar. We plan to be aggressive with listings so when u travel you know where Cripto currencies are adopted. May the better site win as of now they are kicking our ass hahah