When you find a really good keyword, should you go ahead and register all possible/good domains?

e.g. running(keyword).com, webmaster(keyword).com, internet(keyword).com, dog(keyword).com.

I am not going to give away this keyword (might a bit later) but I will tell you that it is an abbreviated word that I have seen many other sites use (and they are pretty good ones too. and when you type it in to google, it seems to recognize this abbreviation as the actual word.

Would appreciate some feedback.