I've been a long-time reader of the site and finally decided to try to create something useful to add to the discussion. As a long-time fantasy player (15 years), I would create a composite list of prospects using the top 100 lists from various websites. I would assign points from 100 for 1st to 1 point for 100th, add up the total points and the sort them highest to lowest. In this way no one site was given more weight than another and I would come up with a list of prospects well over 100 long, which I would use for my league reserve draft.
Anyway, I have created a site in which I have posted these Composite Prospect lists going back to 2008. The 2012 Prospect list, compiles 16 lists from around the web and has over 200 prospects ranked.
You can check it out at: MLB Composite Prospect Index
As you would expect, Mike Moore, Mike Trout and Bryce Harper are all battling for the top spot and are all with 7 points of each other. I expect to add at least of couple more sites in the coming weeks, so be sure to check back for updates.
I hope you find the site beneficial for your fantasy prep or just a fun way to look at prospect rankings.