Marathon Shape Editors

Marathon Shape Editor (MSE) - Pretty simple to use and gets right to the point. Not many functions beyond copying & pasting are available. Supports CLUT editing

MSE was found at:
AMUG, America Online

Marathon Shape Installer (MSI) - Although more advanced than MSE, it crashes a lot more. Supports shape animation. Still in beta stages.

MSI was found at:

Pfhred - Although it is also still in development, Pfhred seems to be the furthest along among all of them. It features shape animation, sophisticated coordinates, clut editing, and more

Pfhred was found at:
AMUG, Info-mac