YADAc is an open source multi company accounting package. It includes modules for General ledger, Inventory, Purchase Orders, Accounts Payable, Order Entry, Professional Billing, and Accounts Receivable.

Currently (June 2009) YADAc is installed at two US locations and is handling all of the user's needs. Updates are rolling out almost daily with enhancements and minor fixes.

YADAc delevlopment is now being hosted on SourceForge.net. Come see the code and possibly contribute at YADAc.