I have downloaded and played around with VST plugins for years, and this, Peak Meter Pro, is probably the most exciting one I have tried for a long, long time.
This VST plugin is the supreme sidechaining utility, bar none. Unlike others which are limited to the traditional sidechain compression, this one allows you to use the amplitude of the sound passing through it to automate anything that can be controlled with MIDI CCs.
Also, where a traditional sidechain compressor or whatever reacts to the amplitude of the sound, sometimes with the option of filtering, this plug filters the sound (just for the purposes of the plugin, it is not audible) and allows you to use the pre- and post- filter, max peak, clip, RMS, for either left or right channel.
Sure, you can get ones that do at least some of the same stuff for free. But not so many of these things at once. For those who actually want or need it, this plugin is the most configurable, easy to set up sidechaining/automation plugin of all I have seen. Compared to others, it is essentially several plugs built into one, with the bonus of a very handsome, easy GUI, as well as very well-written tutorials on its usage at their website.
So if Lemon Sidekick and other sidechain plugs are interesting to you, consider this one, as it's an extremely well-designed and clearly made by a professional outfit.
(BTW, the only features I cannot properly rate here are of course what this plugin sounds like, as it doesn't makey any sound itself, and presets. It comes with no presets, but I didn't really expect any. It's a meter, after all, and will respond to the audio signal passing through it, so I'm not sure about how presets could be used.