So I found this website that custom makes mounts for phones WITH the otterbox communter and otterbox defender cases (different mounts for each case) on. I ordered the 17mm ball mounting plate for my phone (Galaxy nexus) and my wife's phone (Rarz maxx) then I found a garmin nuvi 17mm ball window GPS mount for $8 on amazon that should fit with the cases. Cool stuff.

http://www.slipgripcarmounts.com/