Nightshade UV Editor extends the Maya’s UV Texture Editor with tools, scripts and a UI that greatly speed up the time it takes doing UV work.
The tool does not interfere with other UV editors and does not modify any native files. Additionally NSUV comes with a button for quickly switching to the native editor if/when you need it. Please not that if your studio is using in-house scripts/tools hacked into the native Maya Editor, then you need to edit some rows in core.py for sourcing a custom script.
You can find more details on the toolkit here.