Added this blog post to get that piece of scrap paper off my desk and also to remember these tips by means of typing them in.
Search for pages with both apples and oranges.
apples OR oranges -worms
Either or, not others.
Only the exact word, in PowerPoint presentations.
Include synonyms, but only on that site.
Search after definitions.
Search for ranges, e.g. not the bad 316 model.
Search after sites linking to macworld.com.
Show information about apple.se.
Search for similar sites.
All words beginning with mac, e.g. macworld, macintosh.
Search for routes between airports.
For books with harry potter, select the book icon.
Search for weather information.
Get the current time for other places.
Get the sunrise times, try also "sunset".
10.5 cm in inches
66 GBP in EUR
**Shakespeare wrote ***
Let Google fill in the blanks.
P.S. Of course, Google has its own help page on this topic.