There is the concept of an informational interview -- meeting over coffee to ask about a person's job/industry/company -- but that is distinct from meeting a hiring manager. It may be as effective in the job hunt, although it is not as direct. Consider it, though, as it may be more informative to talk to someone who does a job you'd like to do at a company you're interested in. If that person then recommends you to the hiring manager, you're in a nice position.