Perl module providing hashes with keys that expire after a user-set period

 Hashes tied to Tie::Hash::Expire behave like normal hashes in all respects
 except that when a key is added or the value associated with a key is
 changed, the current time is stored, and after 'expire_seconds' the key and
 value are removed from the hash.
 .
 Resolutions finer than seconds are available if the module finds access to
 Time::HiRes.