I am not aware of any web site, but I could recommend two books. One is the classic(posted 9114 days ago)"The Negative" by Ansel Adams
It will not teach you a lot about the different current films, but it will help you to understand how b&w films react in general, and how you can influence the results.
"Perfect Exposure" by Roger Hicks and Frances Schultz
is a nice and comprehensive book on exposure in colour and b&w, and it will teach you a lot of useful stuff, not only about different films. This book is quite recent (1999), so it also deals with chromogenic and high-chem films.
There is also a book on b&w photography by the same authors, and one purely on the choice of films. I haven't read these (yet), but if they are written in a style similar to that of the one on exposure, they will be nice to read and informative.
For starters, make a decision if you wish to develop films yourself right from the start. It is easy to do, but you will have to get some more equipment. If you wish to try b&w shooting w/o developing yourself, stick with the chromogenic films, such as T-max 400 CN and Ilford XP2, because they can be developed with good results by the store at the corner. (The process is the same as for most colour films.) Also, these films are quite forgiving as far as over- and under-exposure are concerned.
If you come from colour photography, remember that the b&w image contains less information. Some colours, though appearing quite different to the eye, will appear as nearly identical tones in the b&w image. This means that some objects which appear clearly differentiated when you look at a subject, may not contrast with the background at all in a b&w image. To get an impression of what the b&w image looks like, it helps to use a Kodak Wratten #90 filter to look at a subject before shooting it. (See "The Negative".)