Upload & Sell: On
The best of all time was of course, Ultimatte Knockout, but Corel did a damned good job of ruining that. There was a learning curve but you could mask smoke if you wanted. ReMask seems to operate on a similar set of assumptions and I've been using it quite successfully for a couple of years now. There is a learning curve and some of the special tricks from Knockout still apply to make Re-Mask even better than it is out of the box. It does work as a plugin for Photoshop and I think they have a 30 day trial as well. To the person who ripped it for not working on a background layer, there's a good reason that you don't want to do that. You want to configure Re-Mask to automatically dupe the layer you're working on and apply the selection it makes to a layer mask. That way you can refine it after the fact on that new layer in Ps and, more importantly, dupe the masked layer, apply the layer mask, dupe it again and then use the layer matting features as needed (and you dupe so you can mask THAT as well) to perfect your mask.
There are still a bunch of features I have yet to tackle in Re-Mask but overall it works pretty darned well and works on very high res images very well.