Everyone should really follow zagg on twitter. Everyday they do a contest where the __ to the ___ retweets get a FREE invisibleSHIELD and sometimes do other giveaways (some where you pay shipping only) to get free stuff. I just won an invisibleSHIELD.
Edit: I wasn't sure at first if it was just a screen protector or a full body invisible shield and I just got an e-mail from them confirming the order a full body housing.
I wouldn't use one, or any other similar products on the market, even if I was given one for free. These things pick up lint so well they keep your pockets lint-free.