I recently have read the unfinished series "In the Name of the Wind" by Rothfuss (awesome by the way) and have a new appreciation of the bard character. Yet I am no musical talent nor have the foresight or initiative to come up with anything for the various tavern's visited beyond, "there is a bard" which, when it comes down to it, sort of sucks. Would be nice to throw this at them.
I am a huge fan of subs like this that add depth and flavor to the world without commitment. You can slap this in any campaign without affecting it on the macro scale while still adding to the world beyond the PCs.
Also would be fun if you had a bard in the group. When the DM has this in his toolbox then when the PC bard says "I sing for gold" the DM counter and ask, "OK, give me an overview of what you will do and a couple lines because you have to try out against this other bard that already asked to play here."