Enough to run a small business.
Sort of like Quickbooks/Myob, but with customisability through extensible modules.
Franchises (allows a customer to be "owned" by a particular user).
Stock Tracking over multiple stores.
Item import from CSV/Xls files (perl/xls2csv)
PDF generation of invoices for email
Referrer cards system to reward clients
Quote -> Invoice, Invoice -> Purchase Order, Invoice -> Receive Payments, Purchase Order -> Receive Stock functionality.