The amazing versatility of the Linux command-line is a happy and joyous thing, but it also means that however experienced you are, there's always something that you haven't come across before. Command-Line-Fu is a one example. It is a collection of user-submitted command lines (from the short to the line-noise long) that web site visitors vote up or down. You can check out the current most popular ones here.
The very top one when I looked, sudo !!, is something that I knew the pieces of but for some reason never thought of putting together: !! is a reference to the last command issued, so sudo !!runs that under sudo. Perfect when you've just run something and got "permission denied", and quicker than my usual method of using the up arrow and then Ctrl-A to go to the start of the line.
^foo^bar was also new to me: This runs the previous command but with bar replacing foo. This won't always be faster than just recalling the command and editing it, but it's a useful trick.
Possibly more useful is that the default argument is empty. So if you typo a command with an extra letter, you can rerun it with this. For example, ssh myxcomputer, recalled by ^x, would run as ssh mycomputer. Note that it changes only the first occurrence, so it can also be useful in fixing doubled-up letter typos.
There's plenty more useful stuff at the web site. It's well worth checking out and contributing to. You can even get new additions sent to you via Twitter.