Random PCI Slot needs filling.

Okay, I've decided to make the best of a crap computer I got on a budget. I have all the parts I want listed, but I have a spare PCI (Just PCI, not PCI-e... Yes, the board inside is that old...) port that needs filling.
I've got:
The sole AGP port goes to a video card.
1 PCI port is going to an additional cooling fan.
Another PCI port is going to a crappy WiFi card.
...and the one empty one.
Can anyone think of something zany/useful I could use this hole in the back of my computer for?
I've got:
The sole AGP port goes to a video card.
1 PCI port is going to an additional cooling fan.
Another PCI port is going to a crappy WiFi card.
...and the one empty one.
Can anyone think of something zany/useful I could use this hole in the back of my computer for?