What stickers are available to hide the glowing Apple logo on the back of my MBP?
Any sticker will be obtrusive it's is aim is to just mask the Apple logo.  Without you get something to cover the whole rear panel your sticker be as obvious as the logo it's trying to replace, and will probably look a lot worse as there will be some light bleeding through the vinyl unless it's a serious thick sticker, which will then catch on things and have edge-peel issues etc.

Search on Amazon for Macbook and Gelaskins for an idea for covering the whole rear, this is an example:


If you want something smaller, you can use something to take the edge off it by highlighting it in a way that marginally masks it: