I'm not entirely sure what I would use this for though. It seems like I have to constantly update your site with the amount of money I spend, and that is a lot of work just to be able to have a daily budget calculated for me.
I use mint.com, and I don't have to enter anything, everything is just automatically pulled from my credit cards and bank accounts. They let me set monthly budgets for different categories of spending, and let me see if I am on track for my budget or if I need to reduce my spending to meet the budget.