My previous post was about how AA batteries have taken over my life.  The 800s charges NiMH & NiCd batteries (not that anyone used NiCd anymore).  It reconditions and deep charges the batteries.  In addition each battery is charged on an independent channel, so you can charge multiple sets of batteries at varying levels of charge, and they will all be optimally charged.  I use this in conjunction with my MB-D10 and well, it just works.  I use 8 eneloops with 8 backup eneloops, I have never had to dip into the backups, and I shoot a lot.  There is also a small LCD screen on the front of charging unit that shows the status of the charge.  No more guessing whether red is good or blinking green means charging.