This is the table I built for my kids' LEGO collection for Christmas 2009.
The base is made from four slotted organizers from IKEA. The bins (also from IKEA) are made to slide into all the nice slots.
The table top is made from a 5' x 5' piece of baltic birch plywood cut to 4' 8". I rounded the corners of the top, routed 1/8" edge, and sanded it using an orbital sander. I then used spray paint (first coat is white primer, then royal blue -- which matched the blue LEGO color exactly, and then a clear coat) bought from Home Depot.
The kids love it and so do I since their LEGO stuff is now much more organized and stays in one area of the house (though it looks kinda messy in this pictures because of being in the middle of a few new projects).