DReverb

I also got the risk message but on another (freeware) platform you get the direct link and just can place the .dll file into your VST folder. No other files needed for installing.

To the plugin itself: I usually am no big fan of ambient reverbs, as they usually sound too digitally and synthetically to me, but this one really enables some nice, more naturally and organically sounding reverb tones, than I had expected, if properly adjusted. The possible long decay time is a nice additional feature for some self oscillation or drone sounds, although usually some seconds will be the sonically better solution.

Will not replace my (not so cheap commercial) favorite reverbs, but is a nice addition to them. Definitely worth a try.