There was an front-page article in the Wall Street Journal, either 
this month or last, about a man who has made millions doing just what 
you describe.  It discussed many of his tricks, such as scouring 
scientific journals for info and then patenting something vague or 
general related to a technology that looks promising.  Precisely 
because his patents are so vague, they lurk, semi-approved, in the 
system for years.  Of course, he never bothers develop the invention, 
but waits until some other company does and then his lawyers pounce 
with claims of patent infringement.  As I said, he has gotten quite 
rich playing this game!
Mark Crosby