In the late 1980's I had just finished doing a little plumbing at the shop and had some teflon tape laying around. When tuning up a Les Paul and hearing that awful creaking sound the light went off. Teflon is one of the slickest substances around so why don't I try laying the strings on some teflon tape? Bingo! It works great and even helps alleviate the binding on the bridge saddles.
You can find the white teflon tape at most hardware stores for a dollar or two a roll.