This collection of modules has been developed to create a personal new tab with all your own and assigned items. Using these modules will allow you to have a quick access to your leads, emails, tasks, and so on... without having to first click on Menu > Sub-menu > Link, and to filter the result to see the ones which are concern of yours. It's a kind of collection of shortcuts (to see all the links created check the picture below).
So far the OA features are available for CRM (oa_crm), Sales (oa_sale), Document (oa_document), Project (oa_project), Poweremail (oa_poweremail), HR Timesheet Sheet (oa_hr_timesheet_sheet). Before installing one or several of this addon, you first need to install oa_base which will just create the new link in the menu and in the homepage. You can also install all this features at once, by installing oa_complete (then you don't need install oa_base).