Two pages for quickly ginning up a list of professions and services available in a town follow:
S. John Ross' Medieval Demographics Made Easy
Rob Conley's Fantasy Demographics
These are partially based on the 1292 Tax Roll of Paris, which is an interesting historical resource for vocations of the time. Apparently Paris supported one billiadier, or maker of balls for ground-bowling...
I took the liberty of putting them into a .xls sheet:
Town demographics generators
Enter your proposed town population and the two sheets will randomly select professions and craftspeople available within the town - use either generator, or mix and match, depending on your whims and needs.
Note that neither generator guarantees a tavern or inn in a small hamlet - leaving the characters the opportunity to negotiate goods, board, and lodging from the (Reaction Roll) locals...