The hazards of typing off the cuff and not proofing--thanks for catching that! I'll repost (and extend):

C - C#/Db - D - D#/Eb - E - F - F#/Gb - G - G#/Ab - A - A#/Bb - B - C - C#/Db - D - D#/Eb - E - F - F#/Gb - G - G#/Ab - A - A#/Bb - B - C


I'd posted a response to "maple leaf boy", but it seems to have evaporated in the Mudcat ether, so pardon if this is a repeat message. He wrote:

When I first started playing harp I had a C and an A diatonic. Many songs that I sang were in G Major or in G Mixolydian, so I was learning cross-harp very early. Bending the notes was a little tricky at first, but once you get it, it becomes a lot easier.

And using a Melody Maker makes learning the more popular cross-position even easier from the get-go, since you don't need to bend notes to get the basic diatonic notes (only a couple at the extreme ends of the range, and the lower one is an easy bend). But discussing tunings and positions quickly leads to preference wars and confusion, particularly for the folks just wanting to know "which key of harp do I use?"

The problem is that the standard Richter that everyone starts with is probably the poorest choice for playing melodies, as the big gaps in the lowest octave quickly dissuade beginners, who ask, "Where are all the notes?? Why do I have to bend so much to fill the gaps? It sounds so bad!" That's why I recommend either a Paddy or a Melody Maker as a starting or melody instrument. A Paddy has only one note different from a standard Richter, filling the most troublesome gap--sadly, you have to hunt around to find them in the US, or retune standard harps yourself (which is what I've done).

For most types of music--blues, country, rock, jazz--you'll mostly play in cross-position, so to learn cross-position most easily from the get-go, get Melody Makers. You can find some in most large music stores, and they're available in all keys from online purveyors. You probably won't use them much when you start actually playing blues and such--that's when you "graduate" to standard Richters and bending hell--but they're still great for playing diatonic melodies.

Fortunately, for beginners, whether you go with standards, Paddy's or Melody Makers, the answer to "what harmonica" remains the same: you get the same key that you're playing in (for major mode). So if you play "key of G" chords while capoing at the third fret (effectively, Bb), you need a Bb harp.

Once you start playing cross-position on standard Richters, the rules change. That's when you have to apply the "up-5 or down-7" shift I mentioned earlier. So moving from Bb, you'd find that you need an Eb harp to play Bb in cross-position. (It's not really Bb major, but you don't want the grisly details when you're already facing mental overload.) Just note that with a standard harp played cross-position, you can't play straight major; most of the simple tunes you know won't work in this position. That's why, even though cross-harp is the most common playing position, it's not the one most people start with.