Creating and Calling WCF Services in Sharepoint 2010, and Querying them using JQuery

Calling WCF Services using jQuery

http://www.codeproject.com/KB/aspnet/jQuery_To_WCF.aspx

Creating a Custom WCF Service in SharePoint Foundation, using Visual Studio 2010

http://msdn.microsoft.com/en-us/library/ff521581.aspx

Sample Codes: Beginning SharePoint 2010 Development, by Steve Fox,

http://media.wiley.com/product_ancillary/37/04705846/DOWNLOAD/584637c10_CodeDownload.ZIP

http://www.wrox.com/WileyCDA/WroxTitle/Beginning-SharePoint-2010-Development.productCd-0470584637,descCd-DOWNLOAD.html