[Ewing]

Yeah..just be upfront about what you expect from them and vice versa. I tell someone right away that I am licensing the artwork to them to use for specific items and for a specific time period. If they want to use the design for anything else other than what was agreed upon then they need to talk to me about it.
An email paper trail is better than a handshake. Just word it so it says that you are granting them the rights to use the design as a tour poster for bands x and y for whatever time period the tour is. If they want to use the design for anything else, then they need to tell you what for and you need to tell them how much. Also make sure that they give you a decent amount of the posters for you to do as you wish. Don't let them try and charge you for your copies since they're offset copies.