I use:
s search items here
in the address bar in the Opera web-browser (which
effectively works as a command line in this case) to search
using Google.
This saves a lot of typing. I am using a similar shortcut
for searching in ServerFault.
"s" is something I have defined, in menu Tools/Preferences/Search/Add,
Name: StackOverflow - through Google
Keyword: s
Address: http://www.google.com/search?q=site:stackoverflow.com+%s&sourceid=opera&num=%i&ie=utf-8&oe=utf-8
At the time of use the "%s" in the content of the Address field
will be replaced by the actual string, "search items here" in
the example.
By default there is already an entry with the "s" as
keyword, but it can be deleted or changed.
If only questions are to be searched (and not e.g. users)
then the address field would be, using Jonathan Sampson's
neat trick (see his answer):
http://www.google.com/search?q=site%3Astackoverflow.com+inurl%3Aquestions%2F+%s&btnG=S%C3%B8g&meta=