pERP is an eGroupWare ERP Group of Modules, mostly geared towards manufacturing, but very configurable. It requires eGroupWare v1.3+.
There is currently support for:
Fine ACL / basic accrual accounting / Suppliers with catalogs / Multiple stock and manufacturing locations / Bill of Materials.
Of note is the integration into eGroupWare:
Home page bits for Accounts Payable and Receivable / Addresses for Users, Suppliers & Clients are stored in the addressboook / Most parts support linking, and some parts link automatically.