To start things off, we've selected the tune "Star of the County Down" as an enjoyable, fairly simple piece that many people know, and which is both diatonic and chromatic-friendly. We'll decide on tunes by poll in the future, but we were anxious to get started this time!
Star of the County Down is an old Irish ballad and exists in many different versions (and even different time signatures!), so if you search around on YouTube you'll find all kinds of possibilities. Bryan Bowers has a lovely version on his album "Bristlecone Pine." There's some additional information here on Wikipedia.
For those who don't yet know the tune, here's a video of the very talented Ryan Carr playing it:
Sheet music of two different versions is available here:
Josh Birch's version in Am (4/4) -- downloadable audio here
Josh Birch's version in Em (4/4)