the sites ranwithrsd posted should get you the info. you need for tags. Basically you will need to join the MD state Beekeepers Assoc. The treasurer of the assoc. (I believe that is Christine Goldman for this year) will provide you with the form you will need to get the tags from MVA. (The assoc. will ask for an extra fee for this, I think $15 beyond the annual dues of $10.)
I got mine last August. I didn't request a special number and got BEE 0063. Really cool looking tags IMO.