I immediately nerd-sniped myself and started playing with factorials.
Turns out it only goes up to 170!. 170! gives you a number (170 ! = 7.25741562 × 10306). 171! searches for 171 in documents.
Still fun, and pretty darn fast, too. I thought they were probably caching the results for 1 - 170, but they return just as fast for non-integer factorials as well (try 100.2!).
They still could be caching them. The first time they encounter a factorial, they calculate it, throw it in a DB, and it's a quick DB access from then on.
I'm using the date range search option a lot when I am getting outdated search results. Even constructed a quick search for it, so I can type something like: "gdr 30 things" which will then search for stuff from the past 30 days.
Section 4.1 needs to be updated. When you try to use it, Google displays this message on the SERP: "The + operator has been replaced. To search for an exact word or phrase, use double quotation marks."
Another one www.google.com/ncr - sets default Google search domain from google.cc to google.com, where CC is country tld.
Useful if you prefer to search in .com version and not the localized one.
"This-is-*-(dog|cat)"
... but they work. Occasionally you might be accused of being a robot, though.