A couple of months back, Sven-S. Porst wrote about using neodymium magnets for a pinboard. Having something of a profession interest in the matter (my PhD is about a table that floats on magnets), I meant to chime in straight away about the same type of idea I'd had previously. Well, let's just say I've been distracted and/or busy over the last two months. While buying some magnets for some experiments a while back, I also bought one hundred 1/8" by 3/8" cylindrical magnets for the fridge: These are great because their length creates a magnetic field that extends relatively far from the end of the magnet (that is, they're strong even though they don't take up much surface area on whatever they're hold up), and they're also very easy to pick up from the fridge. If you've got especially large fingers, maybe the half inch ones'd be better, though. Now, these aren't your regular fridge magnets. I can stack thirteen of them end-to-end and they still stick to the fridge: I'm amazed how strong these rare earth magnets are, and how cheaply you can now buy them on the internet. Furthermore, you can buy
huge ones, like these one inch spheres. Just be careful of any greater than about half and inch — at large sizes they hurt if your fingers get in the way, and they also are very brittle so their corners and edges will chip off very easily if they smash together. (Not to mention being hard to separate!)
Speaking of smash, it looks like they've got even larger magnets now than they used to. A 4" by 2" by 1/2" block is just asking for trouble, if you can afford the $60 asking price (!). You could secure furniture with magnets that large. I'm happy enough with objects to the fridge for now, thanks anyway.