Hi lbenson,
Sorry about the delay - I've been deep inside the code.
Yes the apad downloads from the PC to the device using wifi. I'm now experimenting with using asus routers and OpenWRT to extend wifi.
I'll get to picaxe in a sec, but to answer what the Android has:
USB host and slave... but the only devices that work are a keyboard and USB memory devices.
WiFi - amazingly simple to use. Browse the internet from any hotspot.
Cat5 - use a wired connection
Microphone, speaker, audio out, camera, 800x480 color screen.
The more expensive ones have bluetooth (which would greatly simplify things)
What it does not have is a way of interfacing with the real world!
So how would you interface to the real world?
Wifi to serial is expensive
Microphone may work (I have an app that runs a FFT in real time on the noise, but no driver yet in Basic. It is coming soon though).
Screen - yes you can turn parts of the screen on and off and detect this with photodetectors but that is a bit clumsy.
Camera. Maybe you can take pictures of leds and decode patterns?
For Apad to picaxe, the audio out might be the simplest. I have just finished writing some code that takes some bytes and creates a .wav file at 2400 baud. Sent it to a op amp and then a max232 and it printed "Hello World" on a terminal program on a PC. Picaxe can talk 2400 baud serial so that is a solution that is at least working with one way data.
I've done some research on WiFi to serial, and many times the best suggestion is an Asus router running OpenWRT. Seems a slightly expensive way to talk to a picaxe though, and it does consume 10 watts.
So in a roundabout way, I seem to be back somewhere near the beginning of this thread looking at interfacing the Cat5 socket to picaxe and to the web.
I looked up the price of the W5100 and they taunt you on the interweb with quotes of $4.22 for volume. But at least that does indicate it is not a hugely expensive chip.
There is a writeup here
http://www.circuitcellar.com/archives/viewable/Eady208/2.html and I'm sure there is more documentation out there.
I guess what interests me is the picaxe talking to the web for the lowest cost and for the lowest power consumption.
But it does open up some intriguing possibilities if you can also use cat5 to talk to an apad. For starters, the apad could act as a keyboard and display for a picaxe. It could also act as an interface between cat5 and wifi and the internet. It could also handle serving up lots of data on a webpage as it has easy access to sd card files.
Where the picaxe shines is the ability to interface to the real world and measure things and turn things on and off.
As an aside, nice comparison of the W5100 and the ENC28J60
http://www.codetorment.com/2009/10/24/arduino-goodness-ethernet-shield/
The W5100 looks very hard to solder. Sparkfun sell some breakout boards. Interestingly, this
http://www.sparkfun.com/products/9476 might be one of the cheapest "ethernet to serial" devices around.
So maybe there are some synergies here to explore?