The folks over at WPBeginner.com have a great list of 15 different hacks for WordPress that they consider to be extremely useful, and I’d tend to agree. Their first hack which enables you to link to an external source from the post title sounds like something Matt Mullenweg could implement on his personal site. One of the useful hacks I found was the ability to use a custom image for the default Gravatar. Simple, but nifty. I’m also starting to see more of this thing called rand which is used to randomize something.
The most useful hack on that post which I’m thinking of implementing myself is the ability to delay the post from being published via RSS for a period of time so that I have a small window in case I need to make a change or edit the post. Couple of other good ones on the list as well so go check them out and bookmark it.