Clive, here is a good site for an old-time tune list, and you can listen to them on MIDI:
http://hetzler.homestead.com/music_2.html(warning: long-winded essay to follow):
The tunes are divided by key: D, G, A, C, and modal. The first four are the obvious major keys. "Modal" in old-time parlance could be mixolydian or any kind of minor, but is most often dorian, frequently with accidentals, and is almost always G or A. "Bluesy" would be considered modal. Tunes are divided this way because the second most important instrument after the fiddle is the banjo, which is tuned so the open strings match the mode of the tune to be played. Concertinist Ken Sweeney is also good at playing this style of banjo (and I think Bob Tedrow does also?)
For some reason, "C tunes" are often more ragtimey than the other keys, with more chord changes and "circle of fifths" progressions. They are more frequently "crooked," meaning not of the normal AABB, 64-measure structure of typical two-part reels. The modal tunes are sometimes connected with old ballads about murdered lovers and such.
Because you don't want to make the banjo player retune over and over again for every separate tune, sessions/jams (or performances, for that matter) are characterized by playing many tunes in a row in one key, then deciding together to change to another key and giving the banjo player time to retune (although he might have to only move a capo). They are also characterized by _not_ playing medleys; instead, the aesthetic is to achieve a zenlike state of chugging along train-like on the same tune until everyone has gotten it out of their system. This is a very good system for learning the tunes by ear!
It is fun to play old-time tunes on the concertina, but I would not take a concertina to any old time jam that I would not take a tuba to. That being said, I put two old time tunes in the Tune-o-tron, Little Billy Wilson and Ways of the World. They are playable on a treble English, YMMV. Also, St. Anne's Reel and Soldier's Joy are perennial favorites you probably know from one of the other traditions.
One last thing: I think American old-time music more closely resembles Scottish music than Irish, in that the fiddlers embellish the tune primarily through rhythmic bowing techniques rather than through extensive left-hand ornaments.
-Eric Root, Floyd County Virginia, one hour north of Mt. Airy,NC, one hour northeast of Galax, VA.