Fruit flies are pesky little buggers, and while sometimes I actually want them around because we are catching food for my kids pets (praying manthis, frog, etc.) I usually don't want them around. The quickest and most efficient way I found to get rid of them is to make this trap.
Use a bowl and inside put a banana peel or apple core (I find a banana peel does work better though) and some balsamic vinegar, red/white wine vinegar, or wine (if you feel like sparing a bit). About a tablespoon of the wine or vinegar is good. Cover the bowl in plastic wrap and then poke tiny holes with a tooth pick in to the top of the plastic wrap in several spots. The fruit flies are smart enough to find their way in to their food but can't figure out how to get out.