I use SplashData's SplashID for all my passwords, bank info or other sensitive data. It also auto wipes if the wrong password is used to many times (you set the number). It also backups on your computer separate from itunes so if you need to use the desktop app to access info you can.
You might also look into MobileMe and the "Find My iPhone" feature. Do not by a subscription from apple, several online retailers sell if for up to 50% off.
Good luck and I am knocking on wood that I don't need to actually use any of these features.