Livecoding is a site where you can watch people code, in real-time. If you sign up, you can sometimes interact with them and other watchers too.

This is, at least potentially, an extremely valuable educational experience, with a whole bunch of fascinating benefits to both watcher and coder. Coders are less isolated and get hints and suggestions as they go, while watchers can see ways of working that may be useful. If the programmer is good, it's great to watch an expert at work and to help learn to think like a coder. If not, there are lessons to be learned, especially from the social stuff going on around them.

Programming has, till recently, been a famously solitary pursuit, apart from in a few methodologies like XP (where pairs of programmers work together), so being able to participate in the act of creation and problem solving, seeing (mostly) smart programmers model their behaviours, and turning it into a social activity, seems like a really good idea. You can get similar benefits asynchronously via things like GitHub, but this is way more personal and engaging, it is not so focused on product, and it is educational in a very different way.

It's actually quite fascinating to watch. Though the pace is seldom racing, it's certainly not like watching paint dry (and some programmers intersperse things with the odd performance, reflection, or chat).

There are channels for many different programming languages, some notably more popular than others, and there's something different to be seen at pretty much any time of day, though not all channels are always busy. 

A similar thing is available at Twitch.tv, though only as a minor channel among a lot of game-watching channels.