It's possible that I have a couple free to play games listed in my collection. Mostly because when we started, Matt converted my collection from our old site's "now playing" list. I've never bothered to go back and clean it up though.
I do list my digital games though. So anything from Steam, XBLA, PSN, Nintendo's eShop all get listed. I do have some free apps for my 3DS listed, mainly so I can quick glance at the list.