As a stopgap measure, you can always use a service that compiles markup, such as TeX, to an image and then link the image into your Question or Answer. Here's a list of some such services taken from a blog post by my good friend Cameron. Reposted below are his sample outputs:

• Codecogs Delivers:

  • GIF

    http://www.codecogs.com/gif.latex?z_t%20=%20%5Cdisplaystyle%5Csum%5Ep_%7Bj=1%7D%5Cphi_jz_%7Bt-j%7D+%5Csigma_%5Cepsilon%5Cxi_t

  • PNG

• mathTeX: Delivers GIF or PNG

• mimeTeX: An older version of mathTeX

• Sitmo Equation Editor: Delivers PNG, possibly others

• mathTran: Delivers PNG, possibly others

jsMath would be awesome as it could allow dynamic previewing of mathematics in questions and answers.

As a stopgap measure, you can use a service that compiles markup, such as TeX, to an image and then link the image into your Question or Answer. Here's a list of some such services taken from a blog post by my good friend Cameron see his blog post for side-by-side comparisons.

• Codecogs: Delivers GIF or PNG

• mathTeX: Delivers GIF or PNG

• mimeTeX: An older version of mathTeX

• Sitmo Equation Editor: Delivers PNG, possibly others

• mathTran: Delivers PNG, possibly others

It seems StackExchange scrubs image links that pass script parameters- which is unfortunate as these services can't be used directly from a post. However, you can download the generated image and rehost using a site like TinyPic.