SKnote has released SDC - Stereo Double Compressor, a new plugin for Windows and Mac OS X in Audio Unit and VST plugin formats with an introductory price of 29.99$.
Including one Optical compressor and a fast, discrete VCA compressor on each channel, SDC is great for mastering and mixing on all kinds of sources, combining the slow, musical action of optical compression to fast and controllable action of discrete circuits.
An internal Mid/Side encoding/decoding matrix makes Mid/Side dynamic control and balance accessible.
Several electroluminescent panels and photoresistors are modeled, together with multiple output transformers.
MSRP is 39.99$.

Now this looks interesting.  The Shadow Hills Mastering Compressor has been modeled via a UAD/Brainworx plugin for a while, and Acustica (makers of Nebula) recently came out with their VST version.  These are very expensive, though -- $200 for Acustica, $300 for UAD.  At $30 for SKnote's take, you probably can't go wrong.
 
Cheers,
Eddie