One evening plots: what worked?

[Suede]

I would like to create some short, one-off plots (perhaps "incidents" or "adventures" might be better terms) that can happen in a single evening with a bare handful of characters...even as few as two or three. Many of us have been around in the game for some time, and I believe that such plots have been run upon occasion.

My question to you is: which of these plots do you remember fondly and as having provided lots of fun for a few hours?

I'm not looking to duplicate these plots, but rather to come up with short plots in the same vein (or artery, as the case may be). Props are always possible, but I'd like to keep them confined to things we already have, or at least things we have with a minimum of modification.

I want to see some action in Arkham. Help me out here.

SB Suede