Here's a simple plugin, it replaces certain text with other text in questions, answers, and comments.
EDIT: now supports regex and html tag substitution
Mostly for simple shortcode replacing, e.g.:
<a href="http://mysite.com/">My Site!</a>
Feedback welcome, the code is here:
Welcome to the Q&A site for Question2Answer.
If you have a question about Q2A, please ask here, in English.
To report a bug, please create a new issue on Github or ask a question here with the bug tag.
If you just want to try Q2A, please use the demo site.