And depending on the state, you can find out the driver's birthday, or even if their real name is different from what is listed on their profile. The site at [0] shows how many states use soundex coding and modulus arithmetic to encode driver's license numbers with PII.

I'd be keen to see if every driver's info aligns with the license number (for those states that use encoding systems that embed PII into the number).

[0] http://www.highprogrammer.com/alan/numbers/index.html