Z.Vex is their name and making tiny tube amps is their game. The iMP above provides a whole .75 watts into 8 ohms and boasts a bunch of other features that make it unique (which I won't go into here). Price is unknown at the moment, but if you are in the market for a micro tube amp for your headphones or really, really, ridiculously efficient speakers, drop by their mildly informative website and take a peek (or their forums which seem to have more info than the site itself).

UPDATE: Price is rumored to be $500.

Z.Vex Home [via Stereo-Fi]