Alice,In my surfing around on those Welsh sites, clicking on midi files just to hear what the tunes sound like I have found that I really like 2 tunes now. The first is called The Maid from the Parish of Penderyn, which someone mentioned a short while back on another Mudcat thread, and I had never heard of it before. The other is called Morfa Rhuddlan or The Red Marsh.
I'm sure that they were both on Barry Taylor's site:
Traditional Welsh Tunes in Midi Format
http://www.islandnet.com/~btaylor/wlshmidi.htm
Helen