MG-Picker Studio is a very intuitive and animator friendly maya picker gui, with powerful features that enable you to create your own customised, free-style picker without any prior knowledge in coding.
Traditional maya picker gui only helps with selecting and command executing, but mgpicker does much more, it serves as an very improved, animator-friendly rig interface.
Check out the snapshots of mgpicker by iAnimate.net for their rigs using MG-Picker Studio:
More snapshots of the mgpicker in practice (from iAnimate.net):
Some more snapshots free pickers for popular rigs:
Availibilty: Windows (maya2011~2016 x86/x64), MacOS & Linux (maya2012~2016 x64)
It is totally free for Maya animator to download the program and free to use the picker file/node designed by picker studio. Charges for picker designers.