As much as I try to hang out my laundry on a clothes line, sometimes I have to use the dryer when the weather doesn't permit sun drying my clothes. So what the heck do you do with dryer lint, other than throw it away? I tend to toss mine into the yard for birds to use in their nests, since I wash my clothes with biodegradable detergents, but there are some other things you can use it for.
A homemade fire starter, by packing a toilet paper tube with it and using it to start a fire in your fireplace or even on your barbecue. Lint is highly flammable, as you probably know, which is why it's important to keep your dryer vent clean.
Indoor mulch for your houseplants
Make dryer lint "clay" by shredding 3 cups of lint into a cooking pot. Cover with 2 cups of water and stir in a cup of flour. Add a half teaspoon of vegetable oil and stir continuously over low heat until the mixture binds together and is of a smooth consistency. Pour onto a sheet of wax paper to cool and use it like playdough.
Make faux Paper Mache by shredding up 3 cups of lint and adding 2 cups of water in a pot. Stire in 2/3 cup of flour and mix well. Cook over medium heat until mixture comes together. Cool on a sheet of waxed paper and use as you would paper mache. You can cover a balloon, a bowl, or wire form with it, letting it air dry for a week to harden. If not using right away, store it in a sealable container for a few days.
Add a bit of it to handmade paper pulp for making paper. (papermaking tutorial here.)
You can make art out of it. The National Lint Project turns it into art. See for yourself here.