I would prefer something automated....It'd be easier, because many of the older #s change very often, and I can't always go back and hand-edit each week.
IMO, if you could allow a "snapshot" of the top-20 for both Japanese and American software, and the next-gen hardware each week, automated, and allow users to wager funds on what will happen.
IE, assign wealth values not only on what you predict, but when you predict. IMO, the Prediction League has gotten rather stale since we have Japanese Sunday estimates from the Source. If we could see a weighted ranking, that rewards people for predicting early, would be neat.
IE:
A person gains some weath (but not much) from post counts, or various forum contributions, as well as registering.
Then they can goto the league, and find a game they want to predict. Let's say Super Mario Galaxy this week. They want to guess BEFORE first day numbers are out. They have the ability to wager with......A 5.0x multiplier on Thursday, and as low as a 2x multiplier on Tuesday (last day of predictions).
When they wager their money, a 100% spot-on guess yields the full payout of 5x on a Thursday guess, or a 2x on a Tuesday guess. A 50% breaks even, and anything lower looses that percentage times 2 (therefore, a 10% accuracy yelds only 20% of your investment).
Thus far, we get nothing for predicting games under current league rules, and such, so accumulating wealth is just as relevant.
A weighted bet can be good too - a double or nothing bet. It could double the payout, but double the cost of a sub-50% vote.
Not only this, if it was automated, a accurate guess now, once numbers were corrected, could spell trouble for those that are poor at predicting.
As for what games to predict: I would ask that you allow some sort of user-submitted content for various games to predict the next week for opening-week releases. This could allow for extra wealth to be gained, and allow for many more fun, niche games to be able to be betted on.
Or, you could go the "weighted" way of defining releases based on strength and hype: an accurate guess on Zack & Wiki would garner a much stronger return than betting on Halo 3's 5th week. This could be inversely calculated based on a pre-defined "rank" of popularity, reviews, and such.
Those are just a few random ideas.