Blood Test Kit
ThinkGeek has a fun blood type testing kit for $9 –

“…a few drops of blood, a little water, and the special card are all you need to find out what blood type you are. In just a few minutes, you’ll have a card which will show you which antigens you have in your blood (which you can compare to a chart in the instructions to determine your blood type). And even better, this kit comes with a laminating sheet so you can carry the card in with you once it dries. Then, you will never not know what blood type you are, and you won’t have to worry about your blood exploding.”Link.

Related:

  • DIY blood smear – Examination of a mammalian blood smear – Link.