I've written a new tool in Python for Autodesk Maya called Nightshade Blockout.
This tool makes creating blockout/selection maps a piece of cake:
-Easy to use, no-bullshit user-interface.
-No need to clone your mesh(es) or use "Transfer Maps".
-One-click automagic color assignment.
-Proper non-overlapping shell padding (aka "Fill texture seams").
-Perfect, shadeless and artifact-free end results.
-Works on multiple multiple meshes (e.g. exploded meshes, etc).
-Smart file paths - auto-corrects missing file extensions.
-Works great together with Nightshade Color Splitter (downloadable here: http://martin.dahlin.net/scripts.html