Google has announced that the Nik software suite is now free. This is a powerful yet easy to use suite including Analog Efex Pro, Color Efex Pro, Silver Efex Pro, Vivesa, HDR Efex Pro, Sharpener Pro and Dfine.
I think I paid $US450 for it some years ago. When Google took it over eighteen months ago, they reduced the price to $US150.
There is good and bad in this. The good is that it is a great product and if you do not have it you should download it and use whichever modules work for you. Silver Efex Pro in particular is an easy and powerful method of monochrome conversions. You can find tutorials here.
The bad is it may have a limited life expectancy. There appears to have been no updates since Google took it over and Google may not be prepared to maintain it for future operating system changes. The question remains whether they are committed to such powerful and easy to use products for the serious photographer or whether in future they will be focused on more superficial products for the mass market.