The Arc AAA is the best tiny light in any type of volume production (there's some amazing custom ones though). You can't go wrong with it, if you don't mind the cost ($25 or so).
The UKE 2AAA eLED is also a very nice light, rugged, lightweight, long running (20 hours), is waterproof to 1000 feet, includes a hat clip for handsfree use, and is less expensive ($11.95 from
www.brightguy.com ) than the Arc. It's about the same brightness as the Arc AAA but has more throw because of a focusing optic. It's about 2x the size of the Arc AAA, roughly the same size/weight as the Arc AA but a different shape.
The CMG Sonic is sort of a cheap imitation of the Arc AAA, less waterproof and generally less nice, $9 at
www.texastacticalsupply.com . It's not a bad light, it's just not up to the Arc's level. Worth considering if you want a 1AAA light without spending much. If you don't mind two AAA's, I'd go for the UKE instead.
The Arc AA is a bigger version of the Arc AAA and is in some sense an improved copy of the CMG/Gerber Infinity Ultra or Ultra-G. The Ultra is $15 or so from TTS or
www.batterystation.com and the Ultra-G (same light but with tougher finish and US govt markings and no retail packaging) is $18.50 from Countycomm, with a $14.50 secret special for CPF members. The Arc AA is basically the same light but a little bit smaller/lighter/nicer and costs $35. In my opinion the Arc isn't worth the large extra cost unless you're a connoisseur. The Ultra/Ultra-G is a CPF favorite along with the Arc AAA.
There is also the 4AAA Princeton Tec Attitude, which uses three LED's and is a great light for camping, but it may be larger than you want for a PSK. It's plasic, but comparable in size and weight to a 2AA Minimag.
For an even bigger light, the UKE 4AA eLED is also highly regarded. It uses four AA's and a Luxeon driven at about 250 mA. It's about 5x as bright as the 5mm LED lights mentioned above, or somewhat brighter than the venerable Minimag 2AA, and it will run for 12+ hours on four AA alkalines with just about perfectly flat regulation.
There's some other possibilities too, but it's easier if you can describe what you want in terms of size, cost, and intended uses.