not a dock, but you can buy bluetooth keyboards that I've been told, can be paired to the s3 (I'm still unsure bewcause I haven't tried it)
and for the nexus, I think ebay had a (generic keyboard) dock that would work, whether it'll will is another matter, as I do not own a nexus
I'll see if I can find it and will repost..
I found the one for the nexushttp://www.ebay.co.u...=item27cdbf46b3
(Now, I'm not sure if this was exactly what you were looking for, but if it is, don't let the 'from hong kong' seller location worry you too much, I buy in stuff from hong kong all the time, my cat6 cable is now 3 or 4 years old, from hong kong, amongst other items)