some options (Score 1)

Been looking in to this area lately and here are some of the options I've come across:

WebERP:
http://www.weberp.org
Lots of activity for the last few months

phpOrganisation:
http://www.phporg.net
For smaller enterprises

Open Accounting :
http://open-accounting.sourceforge.net
Current ly seem to be in the middle of a rewrite

Callisto : http://www.redrocketconsortium.com/Callisto/index. html

HTH