[sbierwagen]

Designing microamp-level systems can be interesting. From http://www.ganssle.com/rants/leaks_and_drains.html :

  I put one of the boards under a microscope and looked at 
  some of the ancillary parts. There's a 22 uF decoupling 
  capacitor. No real surprise there. It appears to be one of 
  those nice Kemet polymer tantalums designed for high-density 
  SMT applications.
  
  The datasheet pegs the cap's internal leakage at 22 uA. That 
  means the capacitor draws a thousand times more power than 
  the dozing CPU.