Lowest power ARM

I'm looking for the lowest power arm with an external bus and MMU. It
should be able to run Linux, even if theres no readily available
toolchain for it. So It should be ARM720T or higher.

The Atmel ARM9 parts are the only ones that support 1.8V external bus,
where I can use low-power SRAM working on 1.8V. Every other ARM is 3.3V
at their external bus, including the LPC2000 ones. I'll probably clock
it down to whatever gives me 10 MIPs but not any lower (Dont want to
run it at 32kHz).

Come to think of it, low-power SRAM will allow me to go down to 32kHz,
but that'll hurt the application.

I have Windows CE 3.0 or higher as a possibility, but linux is the
target for now. I'll even investigate a MMU-less ARM if it has 1.8V
external bus.

any ideas?

Update: I saw LPC3180 and LPC2888 which can run on almost 1V. I dont
know if I can run these on 1.8V to talk to low power sram, or do I
still need 3V somewhere.

The docs on these two are sparce since theyre not in production. I have
no clue how much power theyre expected to take.