I'll cast my vote for P90X. I absolutely love it. It's a well produced set with great routines for all around fitness, and Tony Horton is an excellent instructor. I know a lot of people shy away from exercise videos because they think it's kind of cheesy, but the P90X series does a good job of getting around that, IMHO. I don't know anybody personally that has done P90X and not liked it or seen almost instant results, outside of those who enter the program on bum-knees and throw in the towel after Plyometrics on Day 2.
Now, to be fair, if you have any commitment to do HIIT for 60 minutes a day for 90 days, you're going to get ripped. So you don't necessarily have to do P90X to see those results. Though for ~$120 to own the program for life, it sure beats a gym membership!
Also, one of the nice elements of P90X is that you are free to mix-up the routines after you have the basic structure down, and through repetition you will probably find that after six or seven weeks you can do the routines without needing the accompanying videos, which is a plus in that you can get a workout done in around 30-45 minutes.