Hack for Auto Close Thread and Post Admin Comments

[abhimation]

Hi People,

Badly need this hack which closes a thread which is not active for a certain number of days and automatically posts on behalf of the admin that the thread is being closed because it was inactive.

Any ideas where can I find if it exists? My forum is more than five years old now with thousands of inactive threads.

Any other ideas to retain those posts but save on memory, specially server RAM is most welcome.

Thanks !