Excel and Excel Services

Excel

Simple Connecting an Excel Spreadsheet to SharePoint 2010 List
http://www.fivenumber.com/connecting-an-excel-spreadsheet-to-sharepoint-2010-list/

Formulas Supported
https://msdn.microsoft.com/en-us/library/office/bb862071(v=office.14).aspx

Excel Services

Official blog from Microsoft on Excel Services
http://blogs.office.com/b/microsoft-excel/archive/2009/11/03/excel-services-2010-overview.aspx

Features that cause issues with Excel Services
http://msdn.microsoft.com/en-us/library/ms496823(v=office.12).aspx

Good video and demos on Excel Services
http://msdn.microsoft.com/en-us/office/ff436080

Nice Walk-Through on Excel Services
http://allcomputers.us/windows_server/sharepoint-2010---publishing-to-excel-services-(part-1)-.aspx

http://www.techgrowingpains.com/2010/07/sharepoint-2010-excel-services-failure-and-you/
I logged into the SQL server opened the mapped windows account by opening the following:
SQL server>Security>Logins>DOMAIN\SP_Service
Right click on account select properties. From there go to ‘User Mapping’ and check the target database and add db_owner and public permission set for that user. In addition I added the account ‘DOMAIN\SP_Service’ as the default Schema. Your mileage may vary but you get the idea. Just fill in your domain info as needed.  IISReset Followed