I think Grisbi is the best financial app for the Zaurus, although even then I find it requires a swap file and can be very slow entering data when you have a relatively large number of transactions. I actually compiled GnuCash for pdaXrom once, which required me to also compile much of Gnome as well. After all that effort I found that GnuCash was dog slow and took up way too much memory, so it wasn't really usable in the end.
Dan