When I worked for a financial company a year ago. I've been assigned a task to evaluate a bunch of open source based ERP packages. And one of the interesting one is OpenERP (a loosely derivative of Compiere, which could be extended easily through python instead of Java). Thus make OpenERP slim enough to be developed/maintained by less number of programmer though with strength of Compiere. Learning ERP is enormous task (and should be guided by financial expert), despite I have quit the company too soon before even get a quarter of ERP. I still keep a CHM that I made while learn it.
So here is, It might be worth for those with limited internet connection.
Jut hide the sidebar, it has its own navigation and TOC :))