My husband is horrible about leaving a glass or something on the side table that leaves a ring. These are the mini side tables I purchased at Pier One two years ago when we moved in, and while they weren't a huge investment, I really wasn't looking to find something new for next to our beds, they are little, and that means there is a very small chance of them getting cluttered :)
So I measured the tops, and I went by Joanns and picked up some pre-cut square mirrors with beveled edges from the craft department, cleaned off the tables, laid the mirrors down, and voila! Instant revamp, they reflect light up, cover the ugly water marks, and look oh so pretty, all for about $10, can't beat that!
Simplest - Revamp - Ever!