I did a little something extra for my card this time based on the amazing dies that Laurie Willison of Soapbox Creations has designed. I've bought both and by way of this post I'm asking her to puleeze make some more in other sizes!! They are such a fantastic idea and make what I did below sooooo much easier and prettier!
So my cards hardly ever wind up being standard sizes and I end up making a lot of custom envelopes and having to adapt people's ideas (see Laurie's above) to fit my cards. Here's how I adapted the card hanger idea for my square card: