You can check out  [url=http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=727.0]Static friction/ sliding friction[/url] as an example.

For the Fckeditor: You can find the original html message if you click the first image at the top line.
However, [b]spellcheck/preview[/b] will not be able to get updated content when fckeditor is activated. (Need to modify code to join this two tools.)

*** I just modified the code, the original button turn into "update", You need to click update before you click preview/spellcheck to get latest content from fckeditor.
The fckeditor mode is only available for user who has posted at least 10 message. I did not want it to be available for new user (to avoid message posted by program).

Fckeditor is available at http://sourceforge.net/projects/fckeditor/
Download it and following the instruction from INSTALL.html

P.S. I add javascript code in Theme/default/Post.template.php