Step 1: Garden hose bobbin holder
My solution was to take a piece of garden hose that's 5/8 inch (16 millimeters) in diameter and split it lengthwise all the way down. The bobbins then snap right into the hose and stay very secure until I'm ready to use them, even if I drop it on the floor. The sides of the bobbins are always facing out, so I can easily tell what color thread is on them. An added bonus is that the hose has a slight curve to it, which keeps it from rolling off the table.
I was lucky enough to find discarded garden hose, so it didn't cost me anything. But it would probably look even cooler if you got clear tubing and used that instead.
Step 2: Blocking board pegboard
If I ever need to use it as a blocking board, I'll just take everything off of it temporarily, and voila!
Step 3: Tackle box for presser feet, buttons and needles
Step 4: Neodymium magnet + bolt = pincushion
Choose a bolt that has a flat top instead of a rounded one. It should be about 3/4 inch (19 mm) long, and of course it needs to be attracted to a magnet. You'll also need a small scrap of fabric, a flat piece of metal that is attracted to a magnet, and a flat neodymium magnet. Neodymium magnets are also called rare Earth magnets, and they have a lot of strength and holding power for their size. A regular refrigerator magnet would be too weak to work here. The magnet and metal piece I'm using came out of a discarded computer hard drive.
Sew the fabric scrap into a small pouch that's roughly 2 inches by 4 inches (5 cm by 10 cm). Slip the flat piece of metal inside the pouch. Now snap the magnet on top, and put the bolt on top of the magnet.
If you wanted to, you could just use a magnet and a bolt, but there are several reasons why I settled on this configuration. The flat piece of metal keeps the pincushion standing upright, and makes it easier to pick up. The fabric pouch keeps the metal parts from scratching your tabletop, and enables you to attach it to a horizontal surface, if you wish. I attach mine to the bookcase beside my sewing machine by trapping the top of the pouch between two heavy books. If you need to carry it around, just pull it out from between the two books and take it with you. You could even add a grommet if you wanted to hang it on your pegboard.