If biorhythms had any factual basis, I would be having a stupid day today. But I'm right clever, me.
Get Your Own Biorhythm Chart. EDIT: I made loads of typos in this post. It looks like I got my HTML mixed up, but I can't find the error. Try the direct link instead:
http://www.care2.com/biorhythms/index.html :(
EDIT #6: FIXED EEEET! I'm not as stupid as you look. (That would be impossible.) :)