Baseball Prospectus is doing a series of articles ranking the best prospects in the minors, by position. The first article on catchers is free, but for those who can't be bothered to click the link Max Ramirez shows up at #7:
Ramirez has always hit for average, and has always drawn walks wherever he went, and now he's starting to tap into his power potential with 12 home runs in 250 at-bats, just one off his career high. The question mark remains his defense--his arm is below-average but not awful, but his receiving skills are significantly below average, to the point where many question his ability to stay at the position long term. However, as one scout who went over the list with me said, "Hey, Victor Martinez is still catching..."EDIT: For reference, here's last year's catcher rankings, though this one's not free.