Theres things like:
-"inurl

whatever your searching for)"
Ex: inurl:blabla.txt will bring up a web page who's url contains "password.txt"
-"intext

whatever your searching for)"
ex: intext:gmail invite ; intext:
http://gmail.google.com/gmail/a
- If you put a "*"it replaces a word. one "*" per word.
Ex:"Too many cooks spoil **." Result: "Too many cooks spoil the broth."
-"site

url of a site)" will stay in a certain site.
Ex: "site:
http://www.computerforum.com hello" will search for "hello" in computer forum.
- "~"will search for synonyms.
Ex: ~tips google
-"+" will force google to search a word tht would be ignored because it is spelt like and, or, etc. ex: +OR Original Revew.
- "-" excludes a word from a search.
Ex: -windows -site:microsoft.com
-"link

url of a site)" only searches within a group of sites that link to the site who's url is after "link:"ex: "link:
http://www.miniclip.com tree" will only search for "tree" in sites that have links to miniclip.
-"related

url of a site)" will search sites that have subjects related to the site who's url you typed. ex: "related:www.computerforum.com" will search for other computer forums.
-"filetype

file extension)" will search all files which extension is the same as the one you put in the search. Ex: "filetype:.txt" will find .txt files.
-"intitle

word)" will look for the word searched in the title of the site.
Ex: "intitle:london" will find all sites who's title contains the word london.
-"inanchor

word)" will look sites who's links contain the word put after "inanchor". Ex: "inanchor:amsterdam" will look for a site who's links contain amsterdam.
You can combine these to do very refined searches...
Hope they help,
Regards, Stalex111