My Latex package of the day is ‘siunitx’. No more worrying about flipping and and out of math mode, thinking how best to write an Angstrom or degrees celsius, or forcing units to be in upright fonts. I wish I had known about this years ago!
http://ctan.org/pkg/siunitx
via a very specific google on how to set ‘um’ http://tex.stackexchange.com/questions/522/best-way-to-typeset-micrometers