Rowan:
I agree with Drunken_Mage.... Taking a specific scenario from a longer campaign or module would be a good thing.
Here's a link to one of the articles and the original yahoo groups thread:
http://www.roleplayingtips.com/readissue.php?number=222Some of the scenarios I've most recently run for a 4 hour slot:
Talons of Wong Sheng Shung: Wire Fu Ancient China
Stones of Choga Mish: Ancient Mesopotamia Assault the Zigguraut *-pulled from my ongoing campaign
Cult of Tiamat: Ancient Mesopotamia Rescue the Princess *-pulled from my ongoing campaign
Case of the Haunted Inn: A "scooby doo" / Call of Cthulhu hybrid where everyone except Daphne & Velma died horribly.
Abduction of Kitey Helmsey - a modern/spycraft adventure where TEAM BANZAI has to find & rescue a kidnapped daughter of a Stanford Professor.
Columbian Confrontation - modern/spycraft merc mission where the group has to go to columbia for a prisoner/spy exchange and ends up facing much stranger encounters.
Hallowed Hill - a Dungeon crawl adventure of my own design using some obscure monsters and fun.
White Plume Mountain - The classic module updated for 3.5, This takes 2-4 sessions to complete

More more more more more...
If you are interested in looking at any of these adventures for running on your own, catch me off list.
sponng at gmail dot com
-dr.nik-