I have custom made the slickest personal budgeting and financial modeling spreadsheet.
I just upgraded it so that it uses a rolling average of my expenses for the last 3 months to project out my spending for future months. It auto-adjusts as it gets real data.
Update: Due to popular demand, here is a hollowed out version with fake numbers. Use at your own risk. Please share any feedback or ideas for improvement! https://docs.google.com/…/1lUQVL663f49Or0hFR0MNoj4Zqh…/edit…