What are relative merits of something like a button on a piece of custom bizware that says, "press me to ask for a feature" or "click here if something didn't work right".

The problem I'm trying to remedy is the general lack of formality surrounding feature requests. Most specifically, the rate at which I receive walk-ups from end-users. Taken one at a time, it can be beneficial, but sometimes it can hinder productivity on the larger scale.

Has anyone done something like this and has it been a general success or alternately somewhat a waste of time. My instincts are not giving me a hint here.