Athreshtunes
My first QC iTunes Visualizer. Put this composition in /Library/Compositions and it will be available as an iTunes visualizer. It just vortexes a pseudo-colored version of the album art, and changes aspects of it depending on the volume of the track.

Watercolor Effect
The old "Watercolor" composition done in a way in which it can be placed in /Library/Compositions and used with iChat.

Athresh Effect
This takes the old "adaptive thresholding" composition and turns it into an effect suitable for putting in /Library/Compositions for use in iChat.

Aura Effect
This is a version of the Aura composition that obeys the Image Filter protocol. Thus, if you put it in /Library/Compositions (or ~/Library/Compositions) on Leopard and re-start iChat, it will be available as an effect in Video->Show Video Effects.

Feature Tracker
This composition uses the two feature tracking plug-ins listed on the "Custom Plug-In" download page.

MotionSensor3
A simple frame diff that highlights any motion in the video feed.

SmoothGhost2
This composition fades pixels slowly, causing motion to be blurry.

SparkleTrail1
This was a little hack that left a trail of glowing sparkles behind any motion on the video feed. There are probably much better ways of doing this in 10.5.

HighlightColor
This compositions filters any colors that aren't close to the target color out (replacing them with black and white), and replaces any color that is close with the target color. This makes things that are close to the target color appear to stand out.

MoneyForNothing3
One of the reasons I like the sobel filter for edge detection is that it makes it really easy to find the gradient of the edge-- that is, which direction the edge is pointing. This composition was originally just a debugging tool to make sure the sobel was accurately differentiating the edges. But it looked kind of neat on its own-- kind of like the glowing lines in the old "Money For Nothing" video by Dire Straits, so I put it up on the site.

AdaptiveThreshold2
The "adaptive threshold" technique finds a local value on which to threshold the image. While it's usually used to pull text off a book scanned on a flatbed scanner (where the brightness can vary across the image), when used on video it produced a kind of woodblock-print look that I thought was fun. It's also not very sensitive to lighting conditions so doesn't have to be tweaked as much.

Threshold2
This composition simply thresholds the input video at a certain level, and assigns one color to brightnesses below the threshold and another to ones above. But it can give a pretty funky look if you pick the right colors in the right lighting.

TakeOnMeVideo5
This one is purely about the edges... but with the right lighting and with some tweaks it kind of looked like the stylized drawing in the video for "Take On Me" by Ah-Ha. So I added the spinning thing.

Watercolor
This one flattens the colors, highlights the edges, and composites the two to give a kind of colored pencil and/or watercolor effect.

ComicBook3
This composition uses the Sobel filter to highlight the outlines, fades the colors a bit and makes them more uniform, then puts them all together in a few halftone screens to make a very comic-book look out of a live video stream. I believe the new Quartz Composer implements a similar effect.

Aura
This was one of my most popular ones. It uses an edge detector, blur, and overlay on top of the original image to make certain things in the video input appear to glow.