I do recall a similar themed list from your counterpart Tom Sietsema with the Washington Post and I am very curious to what's good in and around Baltimore. I guess it was easier for him to come up with a list because he is a guy, and that might sound sexist but with the many, many, many times that I have eaten out, I have only seen a woman eat alone once.

I agree with Eric that it's generally easier for men to dine alone, but from a female perpective: Dining solo in Charm City is usually pretty good if you eat at the bar, and if the bartender is a professional.

The Owl bar has always been good for dining alone, either at the bar (dinner) or a table (lunch). Kooper's Tavern in Fells Point is great, as is John Stevens, as long as you are at the bar for both. Kooper's has consistently had fantastic service in the bar area every time I've gone there for the past 15 years, alone and with company. And the food is consistently good too, not gourmet, but always a cut above what you expect. The James Joyce bartenders also take very good care of solo diners, and they are good about reading customers, leaving you alone or being social if you want to talk.

In Baltimore and while traveling, the key anywhere seems to be that when you're solo you should eat at the bar, and you'll feel welcome and be treated well at a good place.

From personal experience i tend to avoid eating at the bar, and would rather eat at a table. Too often as a single woman I've found eating at the bar to signal: single and looking! when that's most often not the case.
Tables tend to provide better people watching, whilst eating at the bar gives you the opportunity to interact with regulars (who are always a great source of information).
Sushi and kitchen bars (such as Roys) are the exception to the rule and I think provide a good entry point to solo dining.

When I lived in Baltimore, I always felt comfortable eating alone (at the bar) at Alonso's, right in my neighborhood. There always seemed to be someone interesting sitting next to me to talk with. I miss that place now that I am in AZ.

Henningers. Eat at the bar. Not only will you have a wonderful meal, you will have a fun and/or stimulating conversation with the bartender and at least 2 other patrons.