A few years ago there was a spate of interest in chromatic aberration
-- fixing footage containing the color fringing, but mostly creating it
for motion graphics and VFX realism. Now, Quba Michalski has a new tutorial & preset (and donate button) in Chromatic Aberration Rig.
Nebulas can be created several ways in After Effects: with "cards in space" of real images, or generated by Fractal Noise or 3D particle systems, commonly fractal-displaced particle arrays like Trapcode Mir, Form, Hitfilm Atomic Particle, and other particle systems.
Andrew Kramer has been the most enthusiastic
provider of footage and tutorials on creating shockwave effects in After
Effects, and recently Daniel Brodesky created something similar, using
Trapcode Particular instead of Fractal Noise
for the base of the effect. There are a few other resources too, more explosion-related examples, but
much of what's been published is outdated or no longer available.
There's another collection of news on tutorials, tips, and related tools assorted with Adobe Premiere, Premiere Pro News Notes #12. There's a bit more about audio this time, though AEP is still playing catchup on Premiere news.