I love the personal touch that photo ornaments add to a tree. I started doing frame ornaments about 6 years ago and have found they become more and more special, each year. You can obviously frame existing photos of family and friends, but I've also tried to frame photos that I've taken at each Christmas. It's fun to look back each year, especially when you have kiddos in your family. I have little cousins that have grown some much, just over the past 5 years and it's great to have that captured in these photo frames.
Where to Buy:
You can find some beautiful frame ornaments at various retailers. Some favorites of mine are Crate & Barrel's reindeer frame ornament (they also have others, just search the ornament collection), and Pottery Barn's Silver Grosgrain frame ornament (seen below). Obviously there is no rule to what you should or should not frame. Frame what has special meaning to you. In addition to family and friends I had to make sure and frame my Westie, McTavish. He's family too after all!