Every spring me and my friends do a martini bar crawl (we have been doing it for 5 years now), and our fav martini's so far have to be:

any of the ones at Ixia - they are expensive, but worth it

espresso martini at Lebanesse Taverna - possibly the best drink i have ever had

dirty martini and thin mint martini at tusk lounge

the Mcintosh Martini at Cosmopolitans

Champps in Columbia, near The Mall in Columbia, has a nice long list of Martinis. Every Wednesday they have half price Martinis and $10 manicures.

Well,if you want a Martini,that's Gin and Vermouth. If you want a mixed drink in a Martini glass well i hear One World makes a good one as well as Dionysus in Mt. Vernon.

I think Shorty's in Canton is known as a martini bar.

I haven't actually had one, but Salt in Butchers Hill looks to have a pretty good martini selection.

Casbar has a great list of nontraditional martinis that they serve for $5 late on Saturday nights (at least, the Saturday I was there!) ... You could do a martini-crawl up Charles St., hitting Copra (if they're ever open) and Ixia's nitro bar as well.

For the suburban crowd, I'll throw out Cibo in Owings Mills (just went there last night and downed a couple of "Bada Bing" Martinis), and 5ive in Cockeysville (best Snickers Bar martini that I didn't make)

Red Star has a nice martini list. I highly recommend the mango martini

Sky Lounge in Federal Hill has a decent selection.