I know many apps that serve this purpose... some better, some worse =) some more focused on home budget, some on personal expenses.. take a look:
HomeBudget Lite (it's quite good even if the paid version is much better);
iXpenselt (that seems to be the best out there, even if it's a bit expensive);
Ace Budget (good and cheap)
Pennies (it's a fair app.. it does what is asked to do and it's easy to use).
I hope you found useful my suggestions,
Cheers,
@nico