Paul, aka "Sariel.pl" is an outstanding builder, but he usually stays within the Technic realm, not much robotics type stuff. He does motorize all of his creations to the extreme which I can appreciate. He has tried his hand at a full scale mechanical arm and done a pretty nice job of it. He has run into the problem that I run into all the time; when you build big, stuff runs ssssslllllloooooowwwww.
You can find him on Facebook where he frequently shows progress on his projects. I am a fan of his on FB and as much as he updates, I wonder if he builds 24/7.