The Microphone Database has 860 microphone profiles and focuses more on newer mics. Each mic has a brief description, the features, as well as the specs, frequency chart, polar plots and review. It's a great place to compare the virtues between several mics before you choose to buy.
Professor Coutant's site looks more at older mics, which makes it a great resource for any microphone history, and specializes in mics used for broadcast. There are some great detailed photos, as well as some seldom seen celebrity user pictures (like the one of a very young Willie Nelson from 1966 on the left).
When I was teaching recording in the early 1990's, one of the biggest problems for my students was one of microphone identification, especially of vintage mics. It was all well and good to discuss using a U-67 or a C-12A, but most students didn't have a clue what they looked like. That's why I dedicated an entire chapter to the microphones that are considered "standards" in The Recording Engineer's Handbook. I tried to give a history of each mic, as well as it's uses. I'd like to think I did a really good job with providing facts that can't be found anywhere else in my book, but sites like Matt's Microphone Database and Professor Coutant's now make it easy for a student to easily identify a vintage microphone. Now if only they were more available to use.
Don't forget to check out my Music 3.0 blog for tips and tricks on navigating the music business.