A calendar that removes todo's on set time.

Actually i would need, and i bet im not alone.. A calendar that all users on the site can enter timestamped events and plans. The plans should automatically be removed on the given time/date.
All plans should be shown on a place so everyone can see everyones upcoming plans.
Not exactly what i am gonna use it for but i will certanly pay for a extension like that..

regards..

Arild@Rygga.se