Freerunner is currently at the top of my list of possibles. Alas it's quite expensive and last couple of reviews I have read said it didn't quite make it as usable mobile phone yet. But watching the openmoko list those guys are pretty busy so I expect that will be fixed soon.
I also have a couple of app ideas that don't need a mobile phone and would do better with a cheaper device.
Ahh the fineprint on that is "every form of I/O you can do the mechanical set up and wiring for yourself", the non-barebones / "computer" gumstix is _very_ _very_ limited on the i/o front.
Aha! I see they have moved one step on... they do blue tooth now.
Thats a bit better, but more or less says...
"Well, our gumstix computer is actually useless,
well, it does have a nifty computer, but it's just going to sit there thinking to itself.
Well you can plug it into a host computer, but there is not much point, because if you can plug it in.. you have already have a computer, the host computer. And the host computer is bigger and can think harder and has lots of peripherals, thats why its a host and I'm a client.
You can buy another computer called a "bluetooth device" which can do the work.
Well, actually the bluetooth device you buy has a powerful enough computer in it already, but it's locked down and proprietary so you can't reprogram it.
Thus the only real reason for a gumstix 400xm-bt computer is the consumer bluetooth devices are closed.
Well, the top'o'the'line gumstix is interesting.
It as ethernet and compact flash II. That means, instead of plugging flash card in, you can plug in any CFII device that can do almost anything...
But wait! That means I'm buying another computer to plug into the first computer because the first computer (the gumstix) has, despite the fact that it, as you claim, can do every form of IO, can't actually do anything! Sigh!
So close, so close,... but no cigar.