Salesforce.com / Data.com Anyone use it?

Use it daily. It's a per user per month fee for a set number of contacts. I think we have 3000/month as a company. They may have other plans, but we do not pay anything extra for each individual contact we import.

Depending on the types of contacts you are looking for, it can be a useful tool. Seamless integration with Salesforce and you can mass import every contact from a company or pick and choose.