Pecunia (http://pecuniabanking.de/) is an Open Source HBCI Banking solution written natively for Mac OS X. It provides maintenance of accounts, loading of bank statements with the built-in HBCI interface, analytics and printing.
HBCI is mostly supported by german banks only. So this application is most useful for german users, not so much others. This is also the reason why the issue tracker and the main (and only) localization uses the german language.
Home screen:
Transfers with accounts and categories: