[OS X TeX] metapost

[Luis Sequeira]

> 
> I wish there was a nice frontend for TikZ...
> 

Well, almost... 
You could try Geogebra. This is a free program that has many educational uses.
Any graphics drawn in Geogebra can be exported in a variety of formats, INCLUDING tikz and pstricks.
(Of course, the code is almost never as clean as a hand-written code, but it works)

Speaking of pstricks, this is an option too! 
For the most part, the drawings the OP linked to can be done in pstricks. If I had the time, I'd do it myself, just for fun.

Luis Sequeira