Hi, Jaeger! Hope you don't mind if I kinda expand on this a bit, as it's something I'd love to see, as well!
Actually, I've been gathering my thoughts and information to create my own request, as echoed by many of the residents of my town. I showed this idea to my TAs in reference to things I'd love to do in our town, and they absolutely loved the idea, as well.
There actually currently IS a bukkit plugin for this kind of thing, called paidswitch. It sets up a sign (like with chests) to place next to switches and buttons. (
http://dev.bukkit.org/server-mods/paidswitch/ )
I'd like to very, very strongly add my voice to this request for mods and admins to see, as it could open up a whole world of new interactions on this wonderful server. Some things of great benefit for my town are: charging admission to a town event or charging to let someone into a special area of town; Dispenser vending machines; having a game where people can choose a certain thing and be charged; operating any variety of town-related things or rides; calling up minecarts; charging to select a destination in a subway system; easy bank donation system...
I could probably go on for a while on the benefits and possibilities this would open up. This would be an amazing addition.
I also thought of reasons why they may choose not to, so it can be open for fair discussion. The best I can think of is that someone could, conceivably, try to make the sign difficult to spot and surprise charge the careless. However, this is difficult to do, as the block in front of it remains empty, you'd have to know what to charge to ensure they have it, and also this seems to fall under the category of griefing and general rulebreaking, as likely as setting up a trap in any number of ways upon walking into a room or TPing, or digging deep hidden pits for people to stumble into. Or even paying someone a lot for something they said they'd give you and having them run off with the money.... It'd be just as controlled, it seems, and with this mod, it'd go without saying that all signs used for switches must be obvious, and remain unblocked. That, and anyone who's been on for a bit would likely learn to check carefully before activating any suspicious switches...
And the benefits would *far* outweigh any possible tricky schemes by rule breakers. The number of possibilities opened here with this are just amazing, and I hope that it's seriously considered for all it could do for us town builders!