Someone from Sunnyvale was asking where you could get openable skylights. When I enquired of a knowledgeable neighbor, he referred me to:
J C Barry Skylights Mfr
559 Campbell Tech Pkwy Ste 5
Campbell, CA 95008
Take careful measurements of the inside and outside of the roof opening. They had a set of dimensions labeled as "eichler" but I think they assumed that you've drywalled the ceiling(!), so don't blindly choose that. Check your own measurements. They can be manufactured in about a week, as I recall.
There are several choices of glass and frame. I kept to the original with an aluminum frame and obscure white glass. Mine had a screen as well--don't know if that was standard but I think so.
You can order electric-powered ones but I was happy with keeping mine manual. For manual, you will have two choices of mechanism, I choose the one that is shorter/less obtrusive. It comes with a pole that quickly does the job. I store mine in the master closet out of sight but handy for the skylight over the master vanity.
I love my replacement skylights and wish I had gotten around to getting them much sooner. In the winter months, condensation from the old ones used to drip down my back when brushed my teeth in the morning or grabbed clothes from the laundry--no more. It's also great on hot summer nights to open them and let the heat in the house escape.