wmbattery is a redone wmapm, it has some features that people may find
pleasing over wmapm:

[quoted from wmbattery website:]
 o  Improved icon layout. I crammed the same information into less space while 
    making the icon more elegant and visually pleasing (IMHO).
 o  Easier to drag onto dock. 
 o  Displays 100% when your battery is full (wmapm is limited to 99% maximum). 
 o  It consumes a little less memory. 
 o  Uses only 8 colors. 
 o  You can run in on a different display via -d (broken in wmapm).

WWW: http://kitenet.net/programs/wmbattery/