For example, : + ) =

This actually isn't important and does very little in improving communication, but it's nice to know which emotions you can use, specially when there is no preview.

PS. Apparently preview can be done using AJAX to submit the text to the syntax parser when clicking a button, and writing the return on a div of it's own.
It's not so hard to do as it first seems, but it depends on the access you have, and how the forum was built.
As long that you have a page (say, render.php) that receives the text in POST (HTML developers know what I'm talking about, input method=POST), does the conversion, and writes the final text, it's rather easy to implement, and you can do it copying examples on the internet.
And I went off-topic, ops :s
Either way, this post is mostly to suggest a emotion cheat-sheat

Thanks for the attention