Karen at Treasured Tails makes a really wide variety of keepsakes from horse hair. The idea is to have a little something to treasure after your horse is gone, or just a keepsake from your favorite horse. There are a lot of craftspeople offering horsehair bracelets for this purpose, but Karen has a real diversity of products - from holiday ornaments, to dream catchers, to fly whisks. There are many items that are quite affordable. You do need to put a little effort in by collecting some tail hair from your horse, though. My horse was quite tolerant, and I spent about 30 minutes pulling the longest hairs of her tail for this project. Karen washes and prepares the hair when she receives it, but you need to pull a good amount for something like a fly whisk.
I ordered a "shufly whisk", similar to the one pictured on this page (scroll down), with a leather-wrapped handle and ten inch whisk, and a wrist strap. It was a surprise gift for a friend, and he was thrilled with it. It is a handy thing to have while riding in the summer, but it also looks kind of neat hanging on the wall (as pictured here). Karen was backed up with holiday orders when I ordered it, but actually finished it ahead of schedule anyway (about 5 weeks in this case), and she returned the hair she didn't use, so I can think of additional projects to make with that.
If you need creative ideas for gifts for the horse people in your life, or want something unique and special made from your horse's tail, take a look at Treasured Tails.