The Baltic is very keychain-friendly, especially with the N-cell or coin cell body. Hopefully pictures will be available on the Peak website soon (when they have enough stock on hand to advertise them).
Another keychain-friendly option is the new cutdown AAA body for using 10280 size Li-Ion cells with a Peak Matterhorn or an old Arc-AAA head modded with a Luxeon LED (
info here). The 10280 Li-Ion cell is the same diameter as an AAA cell but has the shorter length of an N cell. The shortened AAA tube is intended for mods that have placed Luxeon LED's in an Arc-AAA or Peak Matterhorn head, however we did try it with a Matterhorn 3LED Ultra head and it worked. The 3LED Matterhorn head produced about 150cp (about 50% more than normal) when overdriven by the 3.7V Li-Ion 10280 cell. The output was actually very impressive for such a tiny light, although the Peak Snow LED's took on a slight bluish tint from being driven so hard. The Peak designers guessed that the lifespan of the 5mm LED's would be significantly reduced (perhaps 100 hours) by driving them this hard, but no tests have been done on it yet.