Purchase Log
A history of everything I buy. Initially it might just include Amazon, Ebay, Newegg, blinds.com - online stuff captured by Browser plug-ins or DPI. Later we might add the ability of link with my bank to track all credit card purchases.
This would give me the ability to see what model of something I bought, and when, exactly what I paid, find out if the warranty is up, re-order (or check current prices elsewhere), etc.