We started using the AppExchange to get free ideas that would help us set up our business processes in salesforce, this followed 24 months of trying and failing to deploy a CRM from a large software vendor in Seattle. When we first started using AppExchange we were hesitant to pay for marketing add on programs.
We started using InsideView about three months ago and it has fed us a healthy set of leads and information that helps us trigger news stories about target clients. Our sales group has easily adopted the product, I think the best piece of the technology is the slick mash up in salesforce's account record. It took us very little time to implement.