One recent partial solution to this has been to create choropleths with equal representations of subunits with squares or hexagons. They're still not proportional to population (attempts to solve this last hurdle generally result in ugly and/or unrecognizable maps), but they're pretty cool nonetheless.
As soon as the hub-bub started, I thought it would be relatively painless and an interesting exercise to code up a Python script that would make these choropleths. Since they're geometric, it's a cinch to output SVG vector markup. I got about 90% of the way through this project in three weeks, and then a new job and some health issues interfered. but I finally found a weekend to finish it off, in at least a beta, v.0.1 way.
The script is hosted on my GitHub, and here's the IPython notebook/Jupyter tutorial that goes along with it. (There's also a script called Colorbin that's supposed to remove the hassle from associating colors with quantities for the choropleths).
Feedback is welcome. Here are some examples of what the script has produced: