I have found the perfect answer to poor battery life on N900 - get a second device.

I bought an X3-02 a few months ago for my main SIM. It's so small and slim it diminishes the usual arguments against carrying two devices and I have synced all my contacts and calendar from the N900. With a 16Gb Micro SD card and USB OTG, the tiny X3-03 can use the N900 as an external drive and will actually recharge it via the USB adapter.

The second SIM card I now run in the N900 is a Vodafone PAYG and costs just £5/month for 500Mb - hardly going to break the bank. Most of my online time is over WiFi and the battery life is pretty impressive - I can easily get into the second day unless I switch on the phone radios...

When I first bought my N900 I fought hard against the 'It's not a phone - it's a tablet' argument, but I have come to see that N900 really IS fantastic pocket computer with a good smartphone built in, rather than purely a smartphone in itself.

I can heartily recomment the X3-02 as a partner device to the N900 - good telephony, great UI and UX and very decent battery life.

Best of all, provided you can take advantage of WiFi coverage for your data needs, you'll spend less time worrying about the battery of your N900 and more time enjoying all the things it does well.