Todd Kopriva's AE region of interest features a discussion of Dave van Brink, who has a variety of AE projects and scripting nuggets at his omino pixel blog. His free AE filters, the omino after effects suite, are available for both Mac and Windows. He was also one of the original engineers from the QuickTime team, and his QT_TOOLS for the Mac might be be handy for some (for example, qt_proofsheet renders frames of a QuickTime move to a big picture).
Check out Todd's post David Van Brink on After Effects and the link to the Particle Playground and discussion and halftone project shown in the movie below:
There's more on halftones, which are perhaps not as straightforward as first glance may have...
- Effects plug-ins can be used like a combination of Cartoon and CC Ball Action, Particle Playground, Trapcode Form or Particular, Bikini Dots, Frischluft Retrodots, Tinderbox Halftone, Sapphire Halfton, Red Giant Toon It!
- Harry Frank did a tutorial for a Particular Halftone Effect, though it seems lost in the mists of time
- eitei posted a project and demo movie, Create a Halftone like effect with TrapcodeForm
- Chris Zwar did with Halftone effect – using card dance, mentioning a variety of other options (pictured below)