These filters aren't really going to visually blow your mind - I think they're a little more on the techie or specific-use side of things, but that being said, they are very clever & pretty unique so they deserve a mention!
Image processing library for Flash Player: http://blog.joa-ebert.com/imageprocessing-library/
It's a load of cool filters for images in Flash, including some of the more fancy image enhancement tricks that I can't say I've seen anywhere else, like contrast correction, HDR filters, that sort of thing.
I find the best place to find out all of the gory details with this is in the ASDocs, which lists everything. [http://je2050.joa-ebert.com/imageprocessing/]. Now, on it's own it might not seem that groundbreaking, but when you combine some of these effects creatively you get some interesting results. Take the Normalize filter as an example; not much to look at on it's own, but I'm pretty sure I've seen some blog somewhere talking about the Normalize filter being awesome for colour correction on photos. And I'm sure every webcam image could probably use a helping hand from the BrightnessCorrection class or the GammaCorrection class.