I think we tried writing these down once before, but it disappeared.

Anyway, here are the ones I know:

Pipe Hanging: getting a two-Goo-Ball structure to the pipe, then detaching the bottom one. This is used in Leap Hole.

Whacking/Kicking/Thwacking: taking a draggable Goo Ball and throwing it at a structure to move it. A common OCD technique.

Flower Bug: attaching so many Water Goo or equivalent to a single Goo Ball that they swing around and glitch physics, launching the Goo Ball off the structure and somewhere else in the level.

Peter B's Bug/Balloon Bug: clicking a detachable attached goo so rapidly that it glitches and autodisables. In this state, it's "set" in midair, and acts as if a rubber band holds it in place. You can drag it, but it snaps back. It's named after PeterB because he was the first to discover it, in the WoGC, and at first the mods thought he was cheating. It's much easier with Balloons than Draineds.

Well, Peter was using an autoclicker at first.

Slight correction: The flower bug can't be done as easily with Water Goo Balls, as the strand type Rope doesn't activate the bug as much. Only Spring strand types are really good for the bug.

There's also what I like to call the Timebug Beauty Fling bug, where sometimes if you click a timebug in a level with a Beauty Goo Ball, she goes flying off in some random direction. I'm not sure what causes it.

Oh, and the Timebug Fuse glitch, where popping a timebug while Fuses are burning will make the fire stop spreading, and they won't burn up.

I think it's @dwerdwer who first discovered this bug. He discovered this bug three years ago and uploaded the video! (2/21/2009)