Not quite sure where to post this, sorry. But I know lots who post here enjoy macro.
Came across this link in another forum and thought it would be of interest here.
http://www.macrostop.com
He has 4 free online (PDF) books there. Had a quick skim through one of them, and it appears to be very thorough. Covering macro equipment, shootings techniques, focus stacking and more.
Just thought I'd share.