I purchased some Well-Kept Screen Cleansing Towelettes ($6) at Sephora recently because they sounded rather cool! You can get a pack of 15 of these for a mere six bucks and basically they help clean up oil, makeup and other gunk from your cell phones, keyboards, and other devices.
I know, why is Sephora selling device cleansing wipes!? Weird right? But they are actually promoted as a cleansing wipe that acts to keep your skin clear and blemish free as all that oil, makeup, and gunk building up on your phone could potentially cause breakouts or blemishes.