Google has some advanced search features that few people use, which is a shame. Here are some of them, by Karl Hindle. I am sure there are a few more, but these are the more useful ones.

To makes things simpler:

Google advanced search

Exact phrase

"dog poop"

Wildcard word(s)

"dog * poop"

Excluding words/phrases

"dog * poop" -"dog eating poop"

Limit to domain

site:petmd.com "dog * poop" -"dog eating poop"

Find pages that link to somewhere specific

link:krazyworks.com

Search newspaper archive

site:news.google.com/newspapers "dog * poop"

Site information

info:krazyworks.com

Site cache (browse blocked sites)

cache:krazyworks.com

Find related sites

related:krazyworks.com

Define a term

define God

Term origin

etymology bullshit

Search for social tags

@dogpoop

Search hashtags

#dogpoop

Search for products within a price range

"dog * poop" $50..$100

Logical “OR”

"dog poop OR vomit"

Logical AND

"dog poop AND vomit"

Nearby terms

"dog AROUND(10) poop"

Search for all terms

allintext: dog poop vomit

Search for all terms in page title

allintitle: dog poop vomit

Search for all terms in URL

allinurl: dog poop vomit

Include location in search terms

"dog * poop" location:wilmington, de

Limit results to particular file type

"dog * poop" filetype:pdf

Check weather

weather 19810 10 day
weather 19810 hourly

Time somewhere

time moscow russia

You public IP

ip address

Movie showings nearby

movies 19810 regal

Time-limit search result

# Add to results URL
&tbs=qdr:[ymdhns][0-9]{1,}
# y is "years"
# m is minutes, etc

# For example, limit results to the past 30 minutes:
&tbs=qdr:n30