Excessive "Opening application for the first time" dialogs I often get the dialog box warning me that I'm opening an application for the first time.  But, it isn't the first time.  Some of these are applications that I use daily.  

I seem to be getting more of these after an OS upgrade, almost as if some database got reset.  Can I do something to get these warnings to be generated properly?
This warning pops up every time an application wants to register a URI handler (a something:// protocol). Normally, your approval is saved by LaunchServices, but that database can become corrupted. Try resetting it by doing a

/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -kill -r -all local,system,user


in Terminal. The warnings should pop up once for each application again after that, then be gone for good. If they keep coming, something is resetting the database on its own (a clue would be that the default browser / mail app / RSS app / FTP app you set keep resetting to the Apple provided ones).