MDplates.com
MDplates is a joint venture between Jordan Irazabal of Delaware, and Scott Zillmer of Maryland. The goal is to find and photograph every special organization plate that Maryland offers.
Letter: O
| Type | High | Full Name |
| OA | Oriole Advocates | |
| OB | Orchard Beach Volunteer Fire Company | |
| OBG | 0054 | Oldies But Goodies Cocker Spaniel Rescue, Inc. |
| OC | 0047 | Orphan's Court of Maryland |
| OCF | 0092 | IAFF Ocean City Local 4269 |
| OCM | 1883 | Town of Ocean City |
| OCME | Office of the Chief Medical Examiner | |
| OCS | 0001 | Ocean City Power Squadron |
| OES | 0129 | Order of the Eastern Star |
| OF | Oakland Volunteer Fire Department, Inc. | |
| OG | 0040 | Old Glory HOG Chapter |
| OG | Old Glory HOG Chapter (motorcycle) | |
| OGS | 0023 | Ondo Grammar School Old Students Association |
| OH | 0314 | Ohio State University Alumni Association |
| OHC | 0002 | The One Hundred Club of Anne Arundel County |
| OI | Rescue Fire Company | |
| OL | 0017 | Old Line Garrison |
| OLA | Swing Phi Swing, S.F.I. | |
| OM | Owings Mills Volunteer Fire Company, Inc. | |
| OP | 0055 | Ocean Pines Volunteer Fire Department, Inc. |
| OPF | O'Conor, Piper & Flynn Recreational & Social Club, Inc. | |
| OPT | Optimist Club of Maryland | |
| ORG | 0462 | Donate Life Maryland |
| OS | 1015 | Olympic Spirit |
| OV | Odenton Volunteer Fire Company, Inc. | |
| OWL | 0070 | Temple University Alumni Assoc |
| OX | 0039 | Oxford Fire Company |
| OYC | Otter Point Yacht Club |
