Did you know that adding &btnI=745 to the end of a URL in Google will force the "I'm Feeling Lucky" query to kick in and throw you to the #1 result on Google? Well, now you do. Here, take a look at the Google results.
First, let's look at the results for RustyBrick. Add the suffix to the domain and you get directed straight to the RustyBrick Website.
Cool, eh?
My favorite URL extension is obviously disabling personalized search. To do that, add &pws=0 to the end of your URL.
Beware, however: some of these URL extensions can be misleading. Some redirect, for example, to spam sites. Don't always trust every Google URL that you are given.
What are your favorite or not-so-known Google search extensions?
Forum discussion continues at WebmasterWorld.