I rely upon good old passive-aggression and sarcasm. Yes, ignoring does guarantee you will always seem the more mature of the two, and therefore victorious, but it lacks the gratification of a quick quip.
Once, whilst a cashier for a small dollar store, a woman asked me if we carried some sort of car-pump. Again, I must reiterate: I worked at a Dollar Store. We had air-fresheners and ash-trays.
I told her we didn't but because I am clearly so very inexperienced, she was incredulous. I couldn't have possibly known what she was referring to, and how on earth could I have been even remotely knowledgeable of the merchandise I stocked every day? Because she didn't seem to be leaving, I asked her to repeat what she was looking for. She then, very haughtily, began going into great detail-explaining as one would to a small child. She went on and on, growing more frustrated whilst I inserted nods and a perplexed squinting of my eyes intermittently. Once she had finally ceased speaking, I, very calmly, answered "No. We still don't have those."
And then I relished in the pure aggravation that enveloped her. Was it evil? Perhaps. Am I a complete ***** for doing so? Most definitely. But it is so very satisfying.
It has all the benefits of ignoring someone without the sacrifice. If the purpose of this question was to garner ways to avoid confrontation, then no method is really tried-and-true. It really depends upon how pugnacious the second party is.
It's all to do with setting boundaries and finding which ways to communicate these boundaries for each sort of person.