No CRM is fully complete, most organisations need to buy add-ons and extension apps.  Many of these apps run standalone of the CRM, or can integrate with it.  Below is a list I am compiling of complementary solutions to CRM.  If you are looking for to fill a gap you might find your answer here. If you find a cool app that you think should be on the list please email me at This e-mail address is being protected from spambots. You need JavaScript enabled to view it , and I'll add it.

Another great source for apps is salesforces appsexchange, many of the apps on the appsexchange are not sf.com exclusive and support other CRMs too.