There are a number of crafts that can be made from these samples, though of course it depends on the size of the sample piece. Typically the samples come in two forms: large squares bound together in sample books, and pieces sold singly. The latter are usually larger than the former.
I haven't really done a variety of crafts yet with my fabric samples, but I do want to show off what I've made thus far.
Several years back, I gave up using paper napkins for the more eco-friendly cloth variety, and I have sewn my own cloth napkins using fabric samples:
Above, two of the several cloth napkins I've made over time. I don't know why the blue/white/yellow one is a bit larger; I thought I'd used the same pattern for both (pattern and directions from Amy Karol's Bend-the-Rules Sewing book). The blue/white/yellow napkin was made several years ago, which is why it looks a bit rumpled (must have run in the dryer a little too long). I don't remember what I paid for this fabric piece, but I paid a mere dime for the brown/white fabric sample. I recall the price because I just bought it a couple of weeks ago. I didn't have any napkins that looked fall-ish, but this print and the other brown/white samples I purchased at the same thrift store do. And these latest samples are of a very nice, soft, high-quality 100% cotton. I'm sure I'd have to pay a lot more than a dime for a ready-made cloth napkin of similar quality! Very easy sewing too.
The fabric sample books are fun to look at; there is usually a nice variety of prints (and sometimes different types of fabrics) in each. But one problem is the paper strip on the back of each sample, printed with pertinent information (pattern name, fabric care, etc). This paper is stuck on with some sort of adhesive, making it hard to remove from the fabric, so I just cut it away when I was going through one of these sample books awhile back.
This left me with several fabric strips after trimming them away, but I noticed that these strips were the perfect size (about 7 1/2" x 1 1/2") to turn into bookmarks. And that's what I did; below are some of them:
Needless to say, this was a very easy way to make some pretty yet functional bookmarks. And this is good since I always seem to misplace them!