sorry, nate, not real familiar with aberdeen. but if you drive north/east a bit (on route 40) i can help you.
on your way up rt 40 you'll pass the new ideal diner (on your left) -- maybe your best bet if you don't feel like driving far. just outside of aberdeen, it's a total classic, untouched since 1963 or so, and the food is decent, if not earth-shatteringly great.
perryville has the rendezvous, a friendly bar/restaurant (restaurant is in the back) with homemade chow that leans to the tavern side of things, burgers, wings, etc, but also decent crab cakes and fried chicken. in north east, woody's crab house has good crab cakes, soup, that sort of thing. woody's is "nicer", the 'vous a real local joint, and north east is 7 miles further north than perryville which if memory serves is about 10 miles north of aberdeen.
on the way you'll pass through havre de grace, which looks like it would have a decent place to eat. i've spent alot of time there and honestly don't believe there to be one good restaurant in the whole town.
bon appetit! let me know where you end up!