Well suffer no more! (Geez...I sound like an infomercial, don't I?) They have a nifty new product out called the ZipIt Opener.
Photo courtesy of Amazon.
This product is designed specifically to open those hard-to-open plastic packages. It's kind of a can-opener for plastic.
I want one.
(Disclaimer: The link above is a referral link. If you click on that link and buy one of these nifty devices through that link then I will get a percentage of the sale (2%-4%) back as a referral credit. You are not required to buy the item or to buy it through the link should you buy it. The link is only there for your convenience.)