It seems that I've seen plenty of attempts to figure out the whole, "Where the hell are my dry erase markers?" problem. The marker storage solution should be:
Easier to use than not
Oriented to keep the markers inverted so gravity forces the ink to the felt tips
Scalable to accomodate a wide variety and quantity of markers
Simple to install
Again, Velcro to the rescue. Get a long strip of velcro, and stick a long black strip of the hook side along the bottom of the whiteboard. Match the color if you feel so inclined. Then, wrap a band of the loop side near the top of the marker. Presto! Returning the markers back to their spot is as easy (if not easier) then putting them on your desk and forgetting where they are when you need them.
Yahoo! Tip: Getting velcro is as easy as walking over to Facilities walk up help desk on A1. they'll bring out a roll, and you cut your length!