MathJax for the win.

Just a little note that I use MathJax for my mathematical posts, and this is the ONLY scripting (so far) that I throw into my blog.

Here are some of the resources I use for MathJax:
http://meta.math.stackexchange.com/questions/5020/mathjax-basic-tutorial-and-quick-reference
http://www.suluclac.com/Wiki+MathJax+Syntax

and here's how I add it:
http://mathjaxtest.blogspot.com.au/
The one thing missing in this post, however, is that you need to close the </script> tag. :/