All the above suggestions are good, but hopefully at least one or two of your writers know you well enough that they don't really need anything from you. I gave my recommenders a transcript and a resume even though they said they didn't need it. One of my recommenders had me talk to her for 15-20 minutes about my motivations for going into medicine, so that's another thing that you should consider.
One more thing, when you are asking people for recommendations, keep in mind that a personal recommendation from a new/young faculty member is a lot better than a cliche recommendation from a hot shot, well known professor.