Just discovered this yesterday, and I'm blown away.

http://www.pouet.net/prod.php?which=61592

It's a 2-operator FM (actually PM) synth. It's only got 14 parameters. It sounds amazing.

The kicker: the player code is tiny (it's written in x86 assembly). This means you can put together a decent tune with player code in 1-1.5 kb. It was designed for 4 kb intros. Scroll down on the pouet page for a list of examples.

Anyway, it's a very decent synth in its own right, and I'd love to hear what some of the talented folks here could do with it! It's fairly tightly integrated with Renoise, but could be used with other tools.