Good number of links to various FOSS implementations.
Related
Aggregate Navigation With (Almost) No Metadata
dbmsmag.com · · Page
OpenI.org - Open Source web application for OLAP reporting
openi.sourceforge.net · · Page
Building Data Warehouses with MySQL
jeremy.zawodny.com · · Page
Building Data Warehouses with MySQL (Michael J. Radwin's blog)
radwin.org · · Page
mySQL As A Data Warehousing Platform?
rittman.net · · Page
Palo - Open-Source MOLAP
palo.net · · Page
Planning, Budgeting and Analysis (OLAP, Multidimensional, Excel Interface)