I wouild like to find a microcontroller that will handle the following on a single chip (or with minimum support chips)

* Analog inputs - multi-channel
* USB slave or master hardware
* Programmable gain amplifier built in.
* Realtime clock built-in
* battery backed RAM (or suitable alternative)
* Simple web server code for firmware updates and debugging using a web browser
* Built-in buck or boost power converter circuit for converting available power to the voltage supply level of the processor (1.5V battery to 30V unregulated)

and while we are at it... a bonus would be
* Ethernet port built-in
* rs232 level shifters built-in
* rs485 port differential driver built-in

Any Ideas?

 

You ideal micro-controller is non existing, I think. I think you need something like those ARM powered boards. One example is the Raspberry Pi. http://www.amazon.com/Raspberry-Pi-Model-Revision-512MB/dp/B009SQQF9C
Take a look at this catalog also. Perhaps somewhat overkill for your use
http://www.rtcgroup.com/files/2013-IS-Source-Guide.pdf

 

Cypress makes the PSoC(programmable system on a chip), which, I believe, does what you are wanting. They just released a $25 dev board for the PSoC4... making it hobby viable...