Please don't use the propritary innerHTML attribute...

Why? Because it's not a standard, yet?  Frankly, I don't consider this much of a problem.  innerHTML works with all major browsers, and is (almost certainly) going to be part of the upcoming HTML 5 standard (also see HTML 5 differences from HTML 4, section 4.1 and 4.2).

Also, it's in most cases easier to use and understand (and typically faster, too) than the respective combination of 'true' DOM methods.  I figured this might be of advantage for someone just getting started.