I'm a fan of Bill James' Hall of Fame Monitor. As silly as it seems to sum up an entire career in one number, this metric doesn't do a bad job of it, and even manages to fairly compare pitchers with hitters.
However, James suggests that a score greater than 100 equals a likely HoFer, and that seems a bit generous to me. Below the jump is a list of players with scores over 90; for the sake of brevity, I'm limiting it to active players, and for the sake of comparison, I'm combining pitchers and hitters into one ranked list. I'd love to read your thoughts about where you would draw the line, if you would, and whether you think this is a useful metric.
Miguel Cabrera 138
Personally, I'd draw the line around 115. Big Papi's late-career resurgence gets him in, Andruw Jones just misses based on what he's accomplished so far. Thoughts?