Stack based languages resonate with me as a Forth and PostScript programmer!
Please check out this pie menu based visual PostScript debugger for NeWS, called the PSIBER Space Deck, which I hope inspires you, and I'll be glad to answer questions about: http://www.donhopkins.com/drupal/node/97 Source: http://donhopkins.com/home/code/litecyber.ps.txt
One nice thing about PostScript is that it's homoiconic: PostScript code is just PostScript data. So that lets you use a data structure editor as a code editor.
It had a generic set of pie menus that applied to all objects for editing the view and doing standard copy/paste/edit/eval operations, but there was also one object-type-specific submenu to the north-east. So there was a common set of gestures across all objects, that you could learn to use easily.