Seeking suggestions for demo app

[Michael ODonnell]

Our customers typically buy our Linux server
boxes intending to port their custom apps to it
from some other OS, so during the early stages
of negotiations it's not normally possible for
them to take their own app out for a test drive.

I'd therefore be grateful for any suggestions
regarding off-the-shelf FOSS apps that make
for good general purpose demonstrations of a
Linux server's capabilities.  Since a lot of our
customers like Oracle a demo that involved it
along with FOSS would be of particular interest,
but all suggestions welcome.