Add a template entry which holds a list of possible
insertions. While a page is generated, one of the
possibilites is randomly choosen. Maybe something like
this:
<Scrap id="MOTD" type="random">[...]</Scrap>
Further possibilities:
<Scrap id="MOTD" type="rotate_hourly">[...]</Scrap>
<Scrap id="MOTD" type="rotate_daily">[...]</Scrap>
<Scrap id="MOTD" type="rotate_weekly">[...]</Scrap>
<Scrap id="MOTD" type="rotate_monthly">[...]</Scrap>
<Scrap id="MOTD" type="rotate_yearly">[...]</Scrap>