So do they make matching socks? I know this is about 'barefoot' but some of us know our bodies, and in my case if I actually worked out with these - which would be cool - I'd pretty much destroy them in a few days from sweating. Without socks to absorb the moister I'd be concerned about them getting pretty stinky after heavy use.
Now for a specialty shoe, rock-climbing/boulder comes to mind, yeah these would be incredible. In fact, I think I'll probably buy a pair for that the more I think about it. I don't tend to sweat as much climbing.
I've tried bouldering in a borrowed pair. Edging gets painful fast. Far too much stress on my toes. Having separated toes and a relatively pliable sole produces an awful lot of foot strain.
Real climbing shoes are tighter and more rigid. They do just the opposite of what these barefoot shoes do; they bunch your toes together, forming them into a kind of single supertoe. It's probably about as bad for you as wearing high-heels, but it's very effective.
Also, the soles on barefoot shoes are not sticky enough for climbing, so smearing doesn't work too well.
I've done rock climbing in both the five fingers and regular rock climbing shoes. Rock climbing shoes are definitely better 99% of the time, their rigidity helps you to maintain secure footholds.
There's the occasional exception though, I was once able to gain a foothold in the five fingers by sticking my big toe in a hole that fit it exactly.
I've climbed in them before, and they're a bit different to climb in than specialized climbing shoes (I wear 5.10 spires normally). The rubber on the FiveFingers model I tried wasn't as tough as the 5.10 Stealth (which is likely different depending on the Fivefingers model), and climbing shoes also have much better ankle support. In particular, my Spires have a band of thick, tough rubber that covers the Achilles tendon, which is brilliant for heel-hooks. The Fivefingers, lacking that support, made moves like that more difficult.
They do sell toe socks, and I've generally seen toe socks available from other vendors long before Vibram FiveFingers have existed.
You don't really need the socks though, and I've only worn them barefoot. The material is moisture wicking and your feet might get a little stinky but you can just throw the shoes in the wash fairly easily.
That's what I do too and it works. However, my biggest complain is the sole durability. I had mine for a few months (nowhere near 3 years) and the sole wore out to the point where there was a hole on each shoe on the balls of the feet area and I had to replace them.
I hope this issue gets solved with the new 2010 running models (Bikila, Speed) which have 2 additional millimeters of sole.
Unfortunately Speed is only available in Europe, while Bikila is practically impossible to get anywhere. There was another five fingers shoe made with thicker soles and kangaroo hide, but apparently the stitching on the kangaroo hide is weak so they're having problems with seams splitting easily.
I always wear socks with my vibrams, they provide slightly more insulation, and it's just generally more pleasant not to wear the rubber shoes directly.
They are machine washable. I don't wear socks with mine (KSOs) and wash them once a week -- works fine for me. Other people have found that soaking in the sink with 2-3 Efferdent (denture cleaning) tablets also works very well to control odor.
Now for a specialty shoe, rock-climbing/boulder comes to mind, yeah these would be incredible. In fact, I think I'll probably buy a pair for that the more I think about it. I don't tend to sweat as much climbing.