I have been asked this question many times: I have a growing database of tens of thousands of contacts, but I don’t feel like I am utilizing them.  What can I do?  Someone in this scenario will need to start looking into different kinds of marketing automation solutions.  Some of the most popular lead generation software solutions are Eloqua, Marketo, Vertical Response and Constant Contact.
Here is also a great video on Marketing Automation to get an idea of it’s power:

I have used both Eloqua and Marketo for lead generation programs such as lead scoring, lead nurturing, lead assignment, gated forms and many more.  Both companies are very good.  I would have to say that Eloqua is more powerful, while Marketo has a more friendly and intuitive user interface that is designed with a marketer in mind.  Eloqua is currently working on a new release that is expected to be very intuitive as well.

I would recommend keeping an eye on both of these lead generation marketing companies as they are the industry leaders.  They are not cheap, but they both pack a ton of marketing automation power.