For those who do not know, DarkRP is a popular custom gamemode in Garrys Mod. In it you can switch between various jobs with different roles, and salaries. What if this were ported to Minecraft? The money printer function could be emulated via sign text. The "gun dealer" would sell swords, bows, etc. An custom-named stick could be used for arrest/unarrest. The drug dealer could sell potions. I do not mean making it exactly like it is in GMod, but rather adapting it to Minecraft.
I'm trying to make a RP server that works almost the same way. Look forward to that... (It's gonna be a while until it'll be out, though...)