I am in love with photo collages. I used to buy the photo collage frames all the time, years ago. But, I have found that it is so much easier (and cheaper) to just purchase a regular-sized frame and then just create a photo collage on an editing program. By doing it this way, you have full control over how many pictures you include, where they are placed, how they are sized, etc. I thought for sure it would cost an arm and a leg to print out these larger pictures, but to my surprise, it is very economical. I use Shutterfly.com for my printing, and their large-size printing is good quality for a great price. When I do the 16x20 collages (for family members), it costs me around $18 for the print. I have a huge 20x30 frame in my hallway at our house, and it costs only $23 to replace the collage (which I have only replaced once so far).
I typically use Adobe Photoshop Elements (mine is the 7.0 version, but there are better versions available now). There are a variety of backgrounds and options to choose from. I do not like how they require you to pay extra to use all of the backgrounds and such, though. A handful are free and then there are a ton that you can't get unless you pay for a membership, which involves a yearly fee. When you are spending $75 (maybe more now) on the program, you shouldn't have to pay an extra fee just to use it, you know? That's my only beef with PSE. I've still been able to do quite a bit with it, though. I really like the program.
Sometimes I will just do all photographs. Other times I try to incorporate text, whether it be birthdates, a meaningful quote (that I usually find via a Google search), or other words and phrases that are fitting for the theme. These are excellent to give as a gift, especially for grandparents. I purchase one for my mother and one for my mother-in-law, in the frame. Now I just make updated collages that I give typically on birthdays or Mothers Day or even for Christmas. They just switch it out in their frame, and they are all set with a variety of update pictures!
Here are some samples of collages I made. These were all made from scratch, not from templates.