As I said two posts back we use the Community Edition of SugarCRM as our Customer Relationship Management system. SugarCRM is very good and it has a good community behind it. There have been a lot of modules written that extend SugarCRM in various ways, many of which interact with other online systems. I have added a couple to our install of SugarCRM recently. They are connectors that allow interaction with Dimdim and Google Calendars.