Have you tested Picmonkey.com?
It's a web-site where, for free, you can use a lot of tools to edit your photos. Registering isn't needed and you save the edited photos in your computer.
I use it almost daily, because I find it simple and practical.
Recently I found a new funny tool: a collage maker!
I tested it a bit and I love it!
The interesting thing is that there are a lot of layouts to try out: you can make a collage made of squares (a "traditional" layout you can realize using other free tools on the web), but also mixing squares and rectangles in different positions, numbers and combinations. You can even create a layout by yourself.
I made a collage to sum up in images my tutorial about how to make fabric peonies and published it in my Flickr album.
This tutorial is so simple that images are enough to explain the whole process, I think.
Then I put together photos taken in May, a month dedicated to gardening, spending quality time with family and friends and exploring the world :)
I want to make a collage like this at the end of every month: it's a great way to review what we did!
Another idea is to make thematic collages: one about all the bags sewn last year, one about me&S together, one with the photo taken during a specific event...
For example last saturday (national feast here in Italy) we spent a great day in the country with our friends, making pizza in the wood stove and enjoying nature: so I made a collage with the best photos of the day to send it to my friends. In this way you can give them a "souvenir" without swamping their mail box with tons of heavy images.
I'm always looking for free and simple tools to have fun with photos.
Have you web-sites to suggest me? Please, leave a note in the comments!