I thought of one I installed on my PB140...the PowerDoor.
The doors on most 1xx PowerBooks cover the ports and power button. The PowerDoor was a replacement door with an opening for the power button and the internal modem. I'm not sure how much these things cost when new, but it does come in handy if you're not going to be connecting anything to the PowerBook. It also seems to stay on better than the regular door (the majority of PB1xx machines I've acquired are missing their door).
Of course, if you're handy with the hacksaw, you could always make one of these yourself...
The doors on most 1xx PowerBooks cover the ports and power button. The PowerDoor was a replacement door with an opening for the power button and the internal modem. I'm not sure how much these things cost when new, but it does come in handy if you're not going to be connecting anything to the PowerBook. It also seems to stay on better than the regular door (the majority of PB1xx machines I've acquired are missing their door).
Of course, if you're handy with the hacksaw, you could always make one of these yourself...