KMyMoney looks quite promising.
Maybe one of you can investigate the current features of it and report here a short summary?
Certainly for me it has great potential - not all features I would want are in 0.6.2 (eg foreign currency support - although this would not stop me using it now), but it would seem a good candidate for conversion to the Zaurus.
They have a roadmap covering 0.8 and 1.0, so as long as the Zaurus version can have these features added in the future I'd certainly like to see it available.