For who wants to have code in their blog post I would invite you to check out CopySourceAsHtml. [more]That's what I'm using here and seems working fine so far.
For BlogEngine.net there is also [code:C#] <code block here> [/code] but when I used it previously there was no color highlighting so it must be it or there needs to be some tweaks brought about by custom themes.
For those who have access to and would like to use a webcontrol ActivePro CodeHighlighter looks powerful to.
These are just a few and free ones but I like CopySourceAsHtml since whatever color scheme I have in my VStudio IDE, it gets emulated on the resulting HTML.