I'm also a big fan of HIIT cardio; its helped me loose 25 pounds. My current regime (after having been away for the gym for a few months) is on the treadmill. Twice a week, I do the following:
1 min warm up (I do my weights first, so I'm already warm)
45 sec high intensity (at between 7.5 - 8 mph)
1:30 low intensity (2.5 mph)
repeat 8-10 sets.
then, I do a 10-15 minute walk (at 2.5 mph). I was reading an article that said that during HIIT a significant amount of fat is released from stores, and that without a post-HIIT low intensity session that that it is more likely to re-deposit. The low-intensity session apparently burns these up. In addition, I often feel almost queasy after the intervals, so the walk helps alleviate this.