A while ago, Arvid Schneider and Rico Koschmitzky previewed their MtoA Viewport Render Region tool for Maya. arViewportRender allows you to create renders right in the Maya viewport when using the Arnold rendering engine.
This give you the opportunity to make functional use of Maya’s Render View in a more intuitive and practical way. The Render Region tool is built to work with OS X, Linux and windows systems, but only for Arnold Renderer. You can learn more or download the MtoA Render Region tool over at the code repository here.
Along side the arViewportRender, the fellas are also releasing two other tools. One is a custom TxManager, Texture Switch. for handling .tx files/conversions or scene textures in general in a maya scene or .ass file.
The other is a Material ID Manager to handle simple shader mattes.
All of the tools can be found here: https://bitbucket.org/arutils/arutils/wiki/Home