100+ Answers
Michael Godfrey, Engineer, Programmer, Easily distracted individual

I see a few detailed answers here, which in sure are helpful for many. I'll offer a simple one now, based on my own anecdotal experience.

It's on your vehicle registration

Boom, there it is.

I lost my ID once after a night out, and the website to replace your drivers license requires the number. That's the situation that I was in, and this was the solution to my problem.

End Amicus Suspension Fees License Fines Brief Driver's Unpaid For
The Institute for Justice and the Fines and Fees Justice Center filed a brief in Thomas v. Haslam urging an end to driver's license suspensions for fines.Amicus Brief: End Driver's License Suspension for Unpaid Fines and Fees
End Amicus Suspension Fees License Fines Brief Driver's Unpaid For And End Amicus Suspension Fees License Fines Brief Driver's Unpaid For And