This may just be the best free AfterEffects plugin ever. Simply it renders out your straight adjustment layers to a transparent channel for compositing. So you can render out real noise or lens flares without losing the darks with screen (or vice-versa with multiply)! I just can't get over this (ok, maybe it's not actually that cool..). Anyway, all you AfterEffecters should go download this. [link]
Also, this works great with compositing motion lens flares into Flash (but who does that?).