It's hard to predict what'll happen with the steroid guys (Clemens, Bonds, A-Rod being at the top of the list). My best guess is the ones with the stats will get in eventually once voters feel they've waited out enough years as "punishment."
I was happy to see this writer's comments on Roy Halladay, whose career I followed very closely:
I do think Halladay will be a solid candidate. He has solid credentials, including 2 Cy Young awards (one in each league), 2 more runner-up finishes, a perfect game, a postseason no-hitter, an 8-time All-Star, and had several seasons leading the league in various categories ranging from wins to innings pitched to K/BB ratio. Working against him is that he struggled some with injuries and his career ended a bit abruptly, and his final win total of 203 isn’t very impressive on its own (although, with a 203-105 tally, his .659 winning percentage is among the top 20 figures among retired pitchers). I think he’ll get in, though I’m not sure it will be on the first ballot.
Halladay's one of my all-time favorite players, so I'm cheering for him to get in.