The NIK Collection has been revived by DXO with a new version, but the old Google NIK, which is free, can still be found. Which you want to use is up to you, the presets work in both versions. It contains two presets for Silver Efex and two for Analog Efex. There are many more preset here for the NIK Collection, so keep an eye on this website.
Four presets for the NIK Collection to start with.
Selected messages for you
The messages are partly about the same subject, maybe the golden link is there for you. We have already selected them for you so that you can easily read more about this subject.