While browsing the P5.JS docs, I found out that one can instantiate a P5 instance, so one can have a program of object oriented P5 sketches, which is pretty cool, especially with the concept of scoping.
p5.gui looks like a promising library for prototyping sketches or designs for those used to openFrameworks and Cinder.
The d3 block on glitch looks useful for converting datasets between different types (such as geodata which I regularly use in CSV).