I have some latches on my window that are screwed into the sash and allow the window to open only a small distance. The thing can be opened to open the window completely. I want some more of them. Do you know what they are called?

Post a pic.
Probably called Security window latches"

Some may be window manufacturer specific. Mine are.

Will these work? Mag Security 8760 Wedge Type Window Lock , Childproofing-Window Safety (http://www.safebeginnings.com/WebComponents/Catalog/Public/showproduct.asp?id=582&SSAID=372362)

These are called "Wedge locks"

I think this is what you are talking about. Window lock with thumbscrew.
Defender Security Aluminum Sliding Window Lock with Thumbscrew - U 9800 at The Home Depot (http://www.homedepot.com/h_d1/N-5yc1vZ1xh4/R-100212527/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053)