Search contents in a sharepoint site

There are several ways to fetch data from sharepoint 2010. Below are few of the most standard ones, however it is worth mentioning that the list does not include client object model or web services which are equally important aspects.

These methods can be used for:

1. Execute search queries
2. Get enumeration of list items, documents, lists, pages, etc.
3. Get navigation structure either with hidden objects included or without them
4. Iterate through all contents in SharePoint 2010 site

Overview
http://www.codeproject.com/Articles/638734/Basics-of-Sharepoint-Search

Using search API
http://social.technet.microsoft.com/wiki/contents/articles/18202.using-the-keywordquery-class-to-search-sharepoint-content.aspx
http://msdn.microsoft.com/en-us/library/ms544561%28office.12%29.aspx
http://www.dotnetmafia.com/blogs/dotnettipoftheday/archive/2008/02/19/how-to-use-the-moss-enterprise-search-keywordquery-class.aspx

Using site data query
http://msdn.microsoft.com/en-us/library/microsoft.sharepoint.spsitedataquery.webs.aspx
http://www.pointsharepoint.com/2008/08/spsitedataquery-crosslistqueryinfo.html
        --- from a single list
http://social.msdn.microsoft.com/Forums/sharepoint/en-US/f54cdcd1-d2a3-470e-a939-835934e801c4/using-spsitedataquery-to-pull-items-form-specific-lists

Using CrossListQueryCache
http://donahoo-development.com/index.php/2010/04/16/crosslistqueryinfo-and-crosslistquerycache/
 http://bloggingabout.net/blogs/bas/archive/2009/03/27/using-the-crosslistqueryinfo-and-crosslistquerycache.aspx
http://sharepoint.nailhead.net/2008/04/musing-on-crosslistquerycache-class.html
http://donahoo-development.com/index.php/2010/04/16/crosslistqueryinfo-and-crosslistquerycache/

Using ContentByQueryWebPart and CrossListQueryInfo and CrossListQueryCach
http://msdn.microsoft.com/en-us/library/microsoft.sharepoint.publishing.crosslistquerycache.aspx

SharePoint query classes
http://purunep.wordpress.com/2012/04/26/sharepoint-query-classes-and-where-to-use-them/
http://extreme-sharepoint.com/2012/07/17/data-access-via-caml-queries/

SharePoint 2013
http://code.msdn.microsoft.com/office/Query-Search-with-the-372139b5

SPChangeQuery
http://msdn.microsoft.com/en-us/library/microsoft.sharepoint.spchangequery.aspx