I get questions from students and others about what can I do with my swatches etc. To this end, I gathered from the internet a list of ideas for these.
Swatches aside (these should go into a journal of knit/crochet projects with the ball band pattern and a sheet of notes for the next time you want to make the project. This is what the very organized knitter/crocheter does. I'm not that organized.) granny squares and mitered squares can be used for many more things than just afghans. Although this idea is a good one.
You can use a mid sized block for a dish cloth or hot pad, smaller ones make great coasters to protect furniture from drinks. Fold one in half and you can use it for a cell phone cozy, tissue case, eye glass case and more. Sachets from one or two squares stuffed with either cotton balls dipped with a drop or two of essential oil or stuffed with dried flowers make nice gifts when you need a lot and are short on time.
Have 8 or 9 small to medium sized? How about a "cushion" for the back of a wooden rocker or a seat cushion? Double them with different colors on each side that coordinate and you have a reversible and possibly stuffed cushion. Purses, totes, and backpacks are also good ideas. Wallets can be fashioned from 6 squares. Coin purses can be made from 2.
There are patterns for slippers from squares, You could join a few of smaller ones and make headbands, bookmarks or hat brims. Have a bunch? Ponchos are sort of still in style. Baby cocoons are also popular rather than wrapping in blankets.