The top five Open Source Packages used by Companies....

Computer World had an article this week that talked about what 5 packages companies ask for support for and thus must be using.  The list is

1. JBoss
2. Tomcat
3. Apache Web Server
4. Hibernate
5. MySQL Database Server
   

Since I support all of these on a regular basis I have to say it seems like a good list.  What do you think?  What are your top 5 Open Source software packages you support?