Some people have used items such as car headlights (sealed beam) and personally I have built a discharger using peltier elements (link below) or load resistors. My setup can discharge 30A off of a 4S without issue.

My peltier setup
http://www.rctech.net/forum/13467263-post266.html

load resistors
http://www.rctech.net/forum/13487456-post275.html

integy dumper.
http://www.rctech.net/forum/radio-el...r-2s-lipo.html