I started off one campaign with 2 PCs in a tavern when a brawl broke out- one serious enough that the watch got called out. The twosome found themselves cornered in a back alley while trying to escape, so they dove into the sewers.
Then I did a cutaway to the thief pulling a job...and triggering a trap which sent him into the sewers.
Now a triad, they stumbled through the sewers and came upon some smugglers who had someone tied up in a cloth sack in their pirogue. Smugglers defeated, the three became four as they released the captive from the gunnysack- yet another PC.
Etc...
I did this for the entire party, so the "intro" was a running fight through the sewers that ended up in the basement to a different tavern...which they accidentally blew up.
Which got them arrested.
Which, because of the skills they had displayed, got them the option of repaying their debt to society by serving on a D&D version of
The Suicide Squad (the one from the 1980s).
********
Another one featured me letting everyone wandering around an island city-state- think something like Ancient Crete- having a good time at a massive wedding celebration that marked the end of a war by joining the 2 warring sides via the matrimonial ceremony.
On their way back to the mainland, the ship that the various PCs were on- not a party yet, for they had not met each other formally- was attacked by a black, steam-powered ship that appeared from out of an interdimensional portal. The PCs fought the raiders (Anthro Felines of various big cat types) and aaaaaaaaalmost beat them. Eventually, though, they were knocked unconscious...
And awoke-
NAKED- on the beach of some island in another dimension. They are told that they are honored with the opportunity to be prey for the upcoming hunt, and are told to run to the jungle...or end up like the cabin boy: spitted and rotating slowly over a fire about 20 yards away as some of the anthros played instruments and sang songs.
They were told that their equipment had been scattered all over the island, in order to give them a chance.
They, of course, ran for it.
After about 20 minutes of table time the PCs spent running through the jungle and finding the occasional piece of gear, I pressed "play" on my stereo system's CD player: Kodo's theme to [ame="http://www.amazon.com/Hunted-Original-Motion-Picture-Soundtrack/dp/B000005D8L"]The Hunted[/ame] came out of the speaker, announcing
the hunt had begun...