Here's a nice roundup article in Slate on blogs about street fashion.
These blogs are great - as inspiration for sewing patterns and fabric combos, as well as inspiration for dressing up. It also just makes for great people watching.
A few of the best links:
Hel Looks (Helsinki)
Stilin Berlin (Berlin)
Face Hunter (Paris, Berlin, Copenhagen and beyond)
Also, the Japanese street fashion flickr group in endlessly fascinating.