Battery powered, SBC that can run BSD

[John Almberg]

Hope this isn't too off topic... And I'm not sure of my terminology...

I'm looking for a small, single board computer that can run for a  
week or two on batteries (so very low power drain), topped up by  
solar cells when the sun is out, and that can run some sort of  
unix... preferably one of the BSDs. No hard drive, obviously, or any  
other power draining peripherals.

The user interface would be a low powered LCD display plus some buttons.

The application is for a custom measuring instrument that would run  
in a marine environment.

I've been Googling for it for the last hour, but can't find what I'm  
looking for. Any ideas much appreciated.

-- John