Vibram is the company, the only ones that make the 5 fingers. The first time I saw them was on a friend in the gym while he was doing deadlifts, so I'd guess sure, go for legs. I got them originally for trail running when I was in Hawaii, and now I swap between those and my Mizunos for running.
He's a link to the shoe site.
**broken link removed**
Vibram is a large company that makes the soles of lots of shoes, including a large amount of the current military boots. From what I understand, these were made to be "deck shoes" for sailing in the Mediterranean, and ended up being kind of cool. There are arguments by Vibram and supporters on how much better they are supposed to be for your feet, but I guess yo have to read up and decide for yourself.
There are several variations. I have KSOs (Keep Stuff Out), which wrap up to the ankle. If you find a specialty running store in your area they will likely carry them.
Tabi boots is just the name of the style of boot associate with ninjas. No idea who makes any.