They look like Inova Microlight knock-offs. You can get similar ones (but not quite the same) from Lighthound.com under keychain lights. They are Photon II clones, and I just got two from him -- they're quite nice, and have a little constant-on switch along with the momentary switch so you don't have to keep squeezing. 99˘ each.
KevinL, a member of this forums, also sells Photon clones -- and mini ones he calls picolights. I haven't tried either, but many others have had good experience with them.
http://kevin.htgk.org/keylights-orderform.php