I recently decided to give the open-source TikZiT a try for drawing TikZ-based figures. While the feature set TikZiT can handle is a relatively small subset of TikZ's capabilities, it seems to do what it does quite well. I'm running version 0.8.417 on Mac OS 10.6.8 (Snow Leopard), and have only encountered one significant issue so far. Out of the box, everything seemed to work as advertised except for the previewing function. When I asked for a PDF preview to be generated by pdflatex, I'd receive only the relatively unhelpful error message "AN ERROR HAS OCCURRED, PDFLATEX SAID:"
with no indication of what it may (or may not) have said. I have TeX Live 2011 installed (though I see 2012 was released last month), with pdflatex in my path. I did what I could to debug the problem, but a Google search for the error returned no results and the error itself didn't give much to go on. So, I contacted the developer of TikZiT, Aleks Kissinger, who got back to me with the solution within a few hours.
Apparently TikZiT doesn't necessarily use the actual path variable set in your operating environment, but rather searches the two files ~/.profile and ~/.bashrc to attempt to learn the location of pdflatex for itself. The very simple solution was to create or add to one of these files, with a line similar to
in order to tell TikZiT to look in /usr/texbin for the pdflatex executable. Once I'd put that command into my newly created ~/.profile, I didn't even have to restart TikZiT to get a preview of my graph.