At first I was thinking uber sharer but then is be locked down to a specific order of how effects would be applied which I think could yield different results. For example, if I add deferred rendering, I'd want to implement that first before blur or desaturation.
I like the idea of having two textures and switching between them similar to how most implementations of OpenGL use double buffering (ES on iOs is straight render-to-texture IIRC), then render the final product as a quad.
EDIT: I wanted to post this YouTube video that not only walks the viewer through how to create a few common post processing effects, but appears to implement the ping-pong texture example that swiftcoder mentioned (although I have to watch the entire thing still).
Thank you, swiftcoder and Alundra, for your help! I'll post up some screenshots of the results when I can, and then we can deem this thread "RESOLVED".
Edited by Vincent_M, 21 February 2013 - 04:17 AM.