While exploring the component bins, I came across a couple of air variable capacitors, one of which was still in the box and didn't look like it had ever been used. A Hammarlund APC-50-B air padding capacitor, complete with knob. Capacitance range is 3.9-50 pF. Looks in really good condition and turns pretty smoothly.
The other air variable capacitor I found is a little more anonymous but also looked like it hadn't been used before. One of the rotor plates at the very back was slightly bent causing it to make contact with a stator plate. Aside from that it seems in good condition and turns pretty well.
I'll have to see if I can straighten out that one plate. Would be cool to use it in something.