I have noticed this topic pop up a few times.......I am actaully considering putting a page up on my website with a few tricks that might be able to put 50 feet or so on an intermediate level players drive in a few months. anyways, until i do, something you can do that will guaranteed pack a few feet on your drives, and give you wicked snap, is get together a sledgehammer and some old rubber tires and beat the heck out of those tires with the sledgehammer. hit them sideways with backhand grips, forehand grips, overhead. basically give the tires hell for about 50 good reps for starters and work up to about 100 or so. I am currently working on this type of program for some guys in my house, and ill keep you updated on the results. (if anyone even cares anymore, these threads seem to die fast)
The rationale behind all this is the impulse created at the moment you hit the tire is extremely high and replicates the impulse when you release a disc. this is something that cannot be accomplished in the weightroom or with bands/surgical tubing, or even gyro balls, although those may be helpful too. Just some background about me, I am pursuing my masters degree in human performance at UW-LaCrosse, and have thrown field distance drives (slightly) over 500 feet, although I probably average around 440 or so. any questions shoot me an email, and good luck.