Ajaxian just featured a rad comment hack, originally posted by Dirk Ginader, for those times when you need to comment and uncomment a section of code a bunch. By adding or removing just one character you can comment/uncomment an entire block of code. This saves a bunch of time, and works great for just about any language that uses C style commenting.

Here’s how to do it with (X)HTML:

<!--
lorem ipsum dolor
<!-->

Just add a > to uncomment the whole section.

<!-->
lorem ipsum dolor
<!-->

This seems to work in any browser, and validates as both HTML 4 and XHTML strict.