Ab Ripper X from the P90X series was what my friends and I did over the summer during high school and got are "6 packs"
Its an hour video(or 30 min. forgot) do it twice a week for the entire summer and with the proper diet you will get some pretty good results.
Also check out the plyometrics video as well, gives you explosive movement on court. Its what our high school team did for prep before the season, helped a lot.