I have been using the Money program on the iPhone this month to keep track of my finances. This has been very helpful and easy. Instead of carrying around a lot of receipts and entering them in on my computer later, I just keep track of them on my iPhone as i go and there are no receipts in my wallet.
This program is very simple and has its flaws, but overall it is great. The biggest complaints that are due to the roughed out look of the program. It does not seem like there was a lot of time put into the program once it was working properly. There could be a lot more features and options that would make it an awesome program, but I have not found a program that works better for keeping track of money, so this is the program that I recommend.