I used to get a lot of these, until I said enough is enough, and I actually went and got a sign made which I hung over my cubicle. Want to know what it said? It was quite simple. All it said was "If you have nothing to do, Please don't do it here". Alas, that became a talking point too, and I had to start explaining what was the meaning of that sign itself, ie the fact that you cannot do the "nothing" over at my cubicle seemed to tickle them rather than to make them go away. Most of the time, it really seems like they had nothing to do.

Be careful when someone says that they want to talk to you for a little while. That little while usually turns out to be about a quarter to half an hour, and may even stretch long beyond that. So the next time someone asks for a little while of your time, ask them how long it is going to take, and when they give you an answer to that question, you look up your calendar/planner and tell them that you are busy right now, but that you have an open slot in your schedule at such and such a time for that few minutes that they have said they need to talk with you.

This will immediately reduce your exposure to these time wasters, as many people will not have the patience to wait for an appointment, and they can usually resolve whatever it is that they had to consult you by either solving it themselves, or by talking with someone else. So long as they get their issue resolved, they will not find the need to disturb you again.

The other effect of actually setting up an appointment to discuss things, even be it just 5 minutes of your time, lets people know that you take your time seriously, and that they should not waste it. Since you have scheduled a time period to them, they will have to focus on getting their point acros, without rambling on and making idle talk instead. And since they have some time to clearly think about what they are going to talk with you about, this gives them a laser focus and makes them able to formulate their questions to you in a better way.

The key thing is not to allow others to rob you of your time. Dan Kennedy in his book "No B.S. Time Management for Entrepreneurs", calls these people Time Vampires, because they literally suck the time out of you and your schedule.

So don't give in to people who just want you for a "little while". If it is really important, they will have to be content with speaking to you about it at a later time.