The image I started with.
The first one is a free plugin called Virtual Photographer. Virtual Photographer works with Photoshop and Photoshop Elements. If you don't have these programs than you can use it in a free editing program, Virtual Studio, that is made to work with Virtual Photographer.
Virtual Photographer has a large number of presets in which you can make adjustments for things like exposure and film grain. It is a fun program to play around with. There also are a large number of effects that can be used for color images. Unlike a lot of the free plugins Virtual Photographer has a good interface with an excellent preview image area. Virtual Photographer only works with 8 bit images. There are a few more images from Virtual Photographer in the Some Black & White Effects Gallery.
The second plugin is Topaz Black & White Effects. The Topaz plugins used to be fairly inexpensive when I first started using them. However in checking for this post they seem to have experienced some inflation. Even at that they are still are more reasonable than many Photoshop plugins. Topaz Black & White Effects comes with a lot of presets which I used in the images here to give some idea of the things it can do. Unlike Virtual Photographer this plugin has a very large number of adjustments that you can make to your image. I usually find it helpful to find a preset that is close to what I want and then make adjustments.
This is Topaz's idea of a classic b&w image.
With a Sepia/Gold tone.
Topaz does offer a 30 day fully functional free trial. Also in the past they frequently had special offers so that you seldom had to pay full price. Another thing is that it seems that once you buy one of their products you keep getting free updates. At least I haven't had to pay for a new version yet.
There are more Topaz images in the Some Black & White Effects Gallery.