I saw some solar attic fans online at..
Solar Attic Fans
And I think similar products can be had at Lowes or HomeDepot these days.
We have an old AC powered gable fan installed, but the thermostat seems to have
died after 10 or 15 years of use.
So, I'm also thinking of adding some extra ventilation to my attic this summer.
But first, I'm going to stick a wireless temperature probe up there for a few hot days.
If the new ridge vents are working well, I may not need any extra air flow..