I want to help my worrywart wife with a subscription to one of those
web-based IFR flight tracker services. Free would nice, but as far as
I can tell, the free ones cover commercial flights and not GA. What's
a decent one that is cheap that works with GA? I don't want to spend a
meaningful amount of $$$ - this is a total lucury item.

APRS is free. http://www.ew.usna.edu/~bruninga/aprs.html

And it works with both IFR & VFR flights. Of course you have to have a HAM
license and some minor amount of equipment.
--
Ken Reed
http://www.dentalzzz.com