For years I have been budgeting using an excel spreadsheet. With only sporadic success because I had to spend a lot of time with it, entering information from my bank account every month. So a couple of months ago I decided I needed another solution.
I chose Mint
All you have to do is enter your username and password for any account you want to keep up with checking, savings, credit cards, investments etc. You can then set up a budget under any category, many of which they already have or you can enter your own. And it is FREE!
What I like about it is it will send you an email or phone alert when you go over budget on something or when a payment is due. It also pulls your spending into categories and shows you where you are spending the most money. For instance "food and dining" if you click on that it will show all transactions related like the grocery store, dining out etc. You can compare your spending from month to month.
One concern of course was the safety of online budgeting. But this is safer than shopping online. Your banking information is not stored on this site and no money can be transferred or moved by using this site, unlike sites where you shop online and they store your credit card information. Here is more in depth information about safety http://www.mint.com/privacy/