I'm still kinda new to running websites, but here are some tricks that would have helped me in the beginning:
1. link:
www.yoursite.com - Show's you some/most of the links google counts to your page. Handy to find out who is linking to you, or whos linking to the competition
2. related:
www.yoursite.com - find sites google deems related to any given site
3. site:
www.yoursite.com - search the pages of a specific site
4. allinurl: shows only pages with all terms in the url
5. inurl: like allinurl, but only for the next query word.
6. allintitle: shows only results with terms in title.
7. intitle: kind of like allintitle, but only for the next word. "intitle:webmasterworld google" finds only pages with webmasterworld in the title, and google anywhere on the page.
8. cache:url gives you googles cashed (what google has on record) of a site
9. info:url will give you some info about a given site
10. spell: - does a spellcheck (you don't have to do this, google will spellcheck any words searched)
11. stocks: does a search for stocks
12. filetype: does a search for a specific file type, or, if you put a - in front of it, it won't list any results with that filetype
13. daterange: is supported in Julian date format only. 2452384 is an example of a Julian date.
14. maps: shortcut to do a google maps search
15. phone: searches for anything that looks like a phonenumber
16. allinlinks: searches only within links, not text or title
17. allintext: searches only within text of pages, but not in the links or page title
Feel free to add whatever you want
