Our very own Sea Dog here in Bangor has all kinds of Micros on tap. At least I think they would qualify as micros. Good Ales and beers regardless.
But I think the best bet for a crawl-like enviorment would be down in the old port, I think there's only one or two micros down there (I know Gritty's is down there, and I think I've been to another, but for some reason my memory of the place is a bit foggy...) But there are plenty of waterin holes within walking distance.
I don't drink very often but my arm can be twisted once in a while...:D This is the place I like to go in Portland if I want a good pub and food atmosphere.
The Great Lost Bear
There is also Sebago Brew Co. in the Old Port,great stout and a great Hefeweizen
They dont, but I believe 3 Dollar Deweys sells it on tap and they're in the old port
Click herefor the locations of several Shipyard Brew Haus restaurants and Federal Jacks in Kennibunkport