Two random things I like at the moment to get things started:
Making hihats or other metallic sounds using the (mostly) additive algorithm 7.
Having fine control over frequency in this way allows you to make intricate inharmonic overtones with additive synthesis.
Try offsets 0.00 [C], +.036 [A], +.162 [BI], +.103 [BII], maybe some high pass filtering and play it in higher octaves, with a short decaying envelope. Keep all ratios on SYN1 at 1, Mix at center. This setup is useful for a lot of metallic sounds. Try also applying some modulation, remember that the Digitone can do both additive and fm at the same time!
Making chords
Musical intervals can be represented in ratios, and as such we can use those ratios to make four note chords with the offsets. Take a look at this handy chart:
(Just intonation is very nice, but if you want to keep things ‘standard’, you should try the equal temperament ones)
Again, algorithm 7 since that lets us listen to all the operators at once, Mix at center.
Try this for an m7 chord: 0.00, +.189, +.498, +.782