Inline with our department's ideologies to use open source systems, I am now using Lazarus as my front end and Firebird as my backend. It's almost 2 year that i've been using firebird (started by ver 2.1.2) and i really find it a great database. I just started with Lazarus and so far, im already getting the hang of it!
These are the other open source tools that our office is using:
Drupal (our website was made with drupal)
Joomla! (as backup)
Ruby/Ruby on Rails
Python (am still thinking about it)