I've been experimenting with materials for Etextiles for a long time, and one of the biggest issues is conductive thread. It's one of the most important parts of an Etextile project- but it's inevitable hard to work with, for several reasons. The thread by it's very nature is hard to sew and prone to fraying; and secondly the way it is produced leads it to having very high resistance, making lines more than a foot long very difficult to run power through. Lastly, since most of it is actually nylon (or some other synthetic) it's non-solderable, which leads to having to make knots to attach it to components.
So imagine my joy when I found this stuff! I found out about it through a friend who had gotten a sample, but he had written it off as unobtanium. I got it through almost a year of emailing back and forth with the company that makes it. They weren't keen on selling small amounts to an individual, but eventually I think they just sold me some to shut me up (this is a useful skill I've acquired).
This stuff is great. It's actually extremely thin, flat strands of wire wrapped around a kevlar core- so It's solderable! The soldering melts the kevlar but the strands hold up nicely. It works OK in an industrial straight-stitch machine (what we have at Noisebridge) and I'm pretty sure It'd work OK in the bobbin of a home machine. The real kicker is that it has very low resistance- 2.5ohms a yard!
Comparatively, Lamé Lifesaver (my former go-to for thread) has 36ohms a yard and AnioMagic (another good brand) is 24ohms a yard. It's making planning out things like dresses and skirts much easier, not having to figure in an extra couple hundred Ohms in the process.
I have a bunch of 5 yard samples up for sale in my Etsy store. They're $5, but if you send me a really, really good story about what you're going to do with it and how it's going to be awesome and save the world, I'll send you one for the cost of shipping ($2). I'll only be doing 5 of these.