My paint bottles are usually kept in boxes. I try to organize them by color (all the reds go together, all the blues, etc.), but I still have trouble finding a specific colour when I need it.
So, I was pleasantly surprised to find this product: http://www.miniaturicum.de/index.php?infoBox=3&cPath=723
A must-have paint organizer rack for the discerning wargamer!!!