I never thought of the correcting aspect of it. I have noticed that sometimes its hard to figure out just where the bbs are going in comparison to the target so having some zoom could be nice.
I was thinking an acog with a 4x zoom (
http://torontoairsoft.com/product.php?id_product=149 ) would be good just because I like the look better than a traditional scope.
Though this caught my eye but seems a little overboard
http://torontoairsoft.com/product.php?id_product=303