Limit by Date
Many people don't realize that you can limit your Google results by date. On your search results page, click on Tools, then you'll see a menu with choices for different time frames.
The "Related" Operator
A useful operator to use is called "related." This will find sites that are similar to the site you search for. It doesn't work for every search, but when it does it can be useful. For example, suppose you are looking for non-profit organizations that are similar to The Electronic Frontier Foundation (eff.org).
(Be sure there is NOT a space after the colon). You'll find other similar non-profits with this search.
For another example, try this:
For more ways to refine your search with useful operators, see Google's help page, Refine web searches.