I'm going to unscrew the bulb from the fixture and leave the switch up in the "on" position. I hope whatever broke inside will refrain from arcing and catching fire before I can replace the switch.
Could we leave the lights on this time
[Edit 7:59 PM] I've replaced the switch -- fortunately I live near a number of home improvement stores, so securing a new unit wasn't too hard. Copper-clad aluminum, besides being crappy for wiring, also makes your light switches more expensive. This one was $3.27! For a single 15A two-position switch!
PS: Looking in the wall box as I replaced the broken switch made me sad.