CIO Magazine's Christopher Koch has a great matrix of Open Source business models in this month's issue as part of the cover story Free Code for Sale: The New Business of Open Source. The text is pasted below for posterity's sake. All credit to Chris and CIO Mag.
Open Source + Service
What it means: Companies sell support and services around
open-source software.
Whos doing it: Compiere (ERP), JBoss (middleware), Red
Hat (Linux)
Advantages for CIOs: You pay only for support, not
software. The cost to switch providers is relatively low because
the source code is available to anyone.
Startup challenges: Difficult to build businesses because
switching costs are low, …