MAMP is a very easy to install compilation of Apache, PHP and MySQL for Mac OS X. Everything will be installed in one folder. If you want to get rid of it, just move the folder into trash. An easy to use cocoa program to start and stop the servers.
gnuOLAP is a complete OLAP GPL solution with ad-hoc queries, navigation and reporting capabilities. The server system is designed for GNU/Linux OS. Client system is platform indepedent.