Here's what has been on my mind, while my Airnimal Chameleon frame -- to the surprise of my little kids, and the consternation of my wife -- hangs in the living room on my bike stand.
Build a weight weenie-ish folder...
Get a old and/or used crank, remove the outer ring and put on a bash guard; remove inner ring and install a chain catcher/guard; run something like a 39 in the middle ring. (But I would need to get this stuff, incl. the crankset as I'm not cannibalizing a new one.)
Go with a Sram X7 twist shifter and a X7 rear derailleur, and a 9 speed mountain cassette. (All of which I have.) Advantages: no front derailleur; cutting down on cables and weight; simplified set up. Disadvantages: hills; and the hassle of getting the crank stuff. Biggest disadvantage: I prefer drop bars!
I have a new Shimano 105 ten speed triple crank lying around. I could get 105 ten speed STI shifters, and a couple of 105 derailleurs, building a 105 equipped Chameleon. However, I have heard -- this is speculative therefore -- that the Chameleon's cable routing/geometry makes it tougher for STI shifters to do their thing with ease... (Hmmm. Is this accurate?)
Advantages: attractive well specced set up; good for all kinds of riding. Disadvantages: more weight; above all, the potential problem of odd cable routing making shifting tricky and inefficient.
This worry about the Chameleon and STI shifters brings me to Option 2(b), which I am leaning towards:
Use my 105 ten speed triple crank, but get some new Dura Ace ten speed bar end shifters -- the latest version are the 7900 version, very cool with black parts -- on Ebay, and set it up as a bar end shifting bike. Bar ends are also fairly light, though I would have to get some simple hoods and brake levers. Maybe go with Ultegra derailleurs, making the build look like this:
Cranks: 105 ten speed triple
Shifters: Dura Ace bar end
Brakes: Cane Creek SL
Bottom Bracket: Dura Ace
Advantages: a bit of weight saved; bit of money saved; simplicity and reliability of bar end shifters; looks? Disadvantages: no STI's. Possible disadvantage with packing handlebars with protruding bar end shifters?!?!? I like STI's, but realistically this is a travel folder, not a commuter bike. How often would I use it at home? Not THAT much, so perhaps no need for STI's...
Speaking of STI shifters, what's out there? *Checks Ebay* Dang, ten speed STI shifters are pricey! I have older Ultegras sitting around, but they are 9 speed...