what about using an escalating system for keeping draft picks... say if I keep my 10th rounder from last season into this season and I want to keep him again in 2011, he'd be worth a 9th rounder in 2011. Of course, this would mean 1st round picks could not be kept ever since there's no round to move them into next year. That way 1st rounders would always be 'rentals' each season.
also, in case someone keeps more than one FA, I assume the GM would have to spend the next highest pick available for that other FA (i.e. the 14th round pick), right?