Thanks Matthew - I find these invaluable not only in the functions they provide, but also for performing automated "what if's" to see if I can fine tune something manually.
Duncan, Photoshop "actions" are a series of scripted procedures, that's all. What's nice about these is that they pertain to the type of images we like to dabble in - i.e. astronomical.
There are 31 different main actions in Astronomy Tools. Their names
describe what they do:
Construct RGB Image from Channel Files - Create RGB from mono filtered files
Synthesize Green Channel from Red and Blue - Create synthetic green channel
Soft Color Gradient Removal - Remove a color gradient across the image
Hard Color Gradient Removal - Remove a more severe color gradient
Light Pollution Removal - Remove light pollution gradient
Light Pollution Removal Enhanced Flatten - Remove light pollution gradient
Select Brighter Stars - Select stars in your image for further processing
Make Stars Smaller - Make bloated stars smaller, bring out DSOs
Less Crunchy More Fuzzy - smooth oversharpened images, bring out star color
Space Noise Reduction - Noise reduction for the darker areas of the image
Deep Space Noise Reduction - Noise reduction only in the darkest parts
Color Blotch Reduction - Remove only color noise, leaving fine detail intact
Horizontal Banding Noise Reduction - Removes horizontal pattern noise
Vertical Banding Noise Reduction - Removes vertical pattern noise
Fade Sharpen to Mostly Lighten - Get rid of dark circles around stars
Reduce Small Blue/Violet Halos - Desaturate and darken halos around stars
Reduce Large Blue/Violet Halos - Desaturate and darken halos around stars
Increase Star Color - Brings edge color into whited-out stars
Local Contrast Enhancement - Increase contrast between dark and light
Lighten Only DSO and Dimmer Stars - Lighten while keeping bright stars tight
Enhance DSO and Reduce Stars - Make hard stars softer and lighten dim stuff
B&W -> Ha False Color - Convert to color as through Hydrogen Alpha filter
B&W -> Ha False Color Black Space - As above but with blacker deep space
B&W -> OIII False Color - Convert to color as through Oxygen III filter
B&W -> OIII False Color Black Space - As above but with blacker deep space
Star Diffraction Spikes Tiny Stars - Put diffraction spikes on most stars
Star Diffraction Spikes Small Stars - Put diffraction spikes on many stars
Star Diffraction Spikes Medium Stars - Put diffraction spikes on larger stars
Star Diffraction Spikes Fat Stars - Put diffraction spikes on largest stars
Negative B&W - Inverts the image for easy viewing of dim galaxies
Astro Frame - Add a background color border with room for caption
The following 3 additional actions can be applied after a main action
above has been run:
...As Layer On Top - Make 2 layers, action results above the original
...As Layer Underneath - Make 2 layers, action results below the original
...Per Selection Only - Restricts results to the area selected before
i find these an asset myself, they really help me overcome some problematic images!- as a matter of fact, noel has a new Star Spikes Pro program out, i've been using it a little and found it a great tool to highlight some my images, i noticed on some of my oblong or out of shape stars, it makes them look alot better and even controls star bloat!- heres a link to it- john http://actions.home.att.net/
The way I use them, is to (Win) Ctrl-J (copy) the Background (BG) Layer as my to-be “Actions” layer. Then I make the new Actions Layer active by selecting it and de-eyeball the BG Layer so the Carboni Action(s) only runs on my selected Layer.
i think i did pay 19 dollars for the first release of actions. 
