Smalltalk reifies the stack as objects you can manipulate. Interestingly this allows even serialising continuations! https://news.ycombinator.com/item?id=10099817
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Extraterm is a terminal emulator with a really interesting model of showing outputs in frames and allowing you to manipulate them:
Pandas is wonderful. It's really easy to grab some data, manipulate it, then graph it. It even renders better than lists in ipython.