First you make a proper webpage using the rich text editor that also supports tables, images and Flash movies. Then set the time when you want that web page to expire (or become unavailable).
When others are reading that webpage, they will also see a count down clock that shows the exact time to disposal.
Disposable WebPage provides a wiki like environment where others can also edit the web page created by you provided you share with them the password (or the master key).
Could be a useful and quick alternative to small wikis for managing upcoming events and TODO lists. disposableWebpage.com