Currently, just one plugin is available, though hopefully more will follow. For now, follow the link to the pages for each plugin to get to the downloads area. Eventually I'll make plugin bundles available for download here, but there's not much point in doing that yet.
Synthetic HDR is an algorithm that makes it possible to synthesize greater dynamic range versions of existing images, without affecting the tonality of the original image and without introducing unpleasant artifacts. Though it isn't specifically intended as a noise reduction algorithm, in practice it has that perceived effect.