Lpc2000

> If you have just a few bytes to save, you can keep Vbat and 
> use the alarm registers of the RTC and probably the RTC 
> registers itself  if you don't mind loosing it (you probably 
> will have to pull X1 down and select external  oscillator, or 
> select the clock derived from the main oscillator and keep 
> resetting the seconds register to avoid changes in the others).
> But if you need more than a few bytes, then go to an e2prom 
> or even a serial dataflash. They will give you a lot of non 
> volatile memory using just a few i/o pins (2 or 4).

....Or use the flash on the lpc. There is Philips software on this yahoo
site that emulates an EEprom device using one (or more) flash segments.
It's reasonably smart in terms of not needing to erase the whole segment
till it's been filled.
I have used a modified version of this for both a logging and a
parameter storage application and it works fine. Beware you'll need to
disable interrupts during IAP calls, and if your application can't allow
this you'll have to copy some code into RAM (see other postings).