I've used the Nik photo processing software before, years ago, and it's really excellent stuff. Last year when I bought a new camera I had noticed that Nik had been bought by Google and they were offering the whole bundle for $100 or so, which seemed like a bargain. However, I spend way too much on plugins already and so convinced myself that I didn't need it. 
 
Just went back to take another look at it and I see that the whole lot is now a free download? What a boon! These are really amazing programs. What incredible times we live in. Thanks Google! 

Can you help out those poor, abused celebrities in that other thread with this new plug-in? 

 
Excellent set of plug-ins.
 
I think they've been free for about a year now James. If I remember correctly, the only 'price' to pay is that development has ceased so there will be no updates/improvements to them.
 
I do find that it can be easy to over-process with them - they don't really seem to do 'subtle'. As Photoshop adds a Nik filter as a new layer, what I tend to do now to tame their effect is to either use a layer mask to selectively apply them or bring down the opacity of that new layer to fine tune.

I installed in paint.net.
 
Not sure what they do, but they are free !
 
Jeff

I find like most things the presets or defaults are always way over the top (a bit like synth presets I suppose) but you can dial them back considerably for a more subtle effect. And the other thing to remember as well is that not every photo responds well to a particular filter - sometimes depending on the tonal balance, and dynamic range and content of an image, the filter can end up making it look either garish or really nice. 
 
To be honest the only ones I was really excited to have were Silver Efex and the RAW presharpener. The sharpening is quite a bit better than that offered in Lightroom imo, or at least that's the case with my Fujifilm camera anyway. It did quite a nice job on this: