What registry keys/files are modified by installers?

"AppDeploy.com is a website dedicated to collecting tips and information on deploying (and removing) apps.

It's aimed more at a sysadmin audience, who'll be using automated deployments using silent install techniques, but equally holds an awful lot of info on how various installers and app installs work."

As harrymc mentioned, there isn't a site that documents all registry keys modified by products very well. To find out exactly what an installer's doing, I typically use Process Monitor from Sysinternals and filter by the application name (eg. setup.exe). You can also save the capture and look through it later. Various filtering options make it easier to pinpoint registry modifications as well.