A search engine will be the best database in this circumstance. Your inquiry is specific enough that any firm meeting your criteria should be easily discovered through a combination of carefully selected keywords. Any firm not revealed either (1.) doesn't fit your criteria, or (2.) has no real understanding of online marketing. If they can't do it for themselves, what would make you think they can do it for you? Trust your search engine.
A Note From The Editor
Free Webinar: How to Use Customer Service as a Marketing Tool
Tune in October 12th as we highlight some of the best tools to create brand loyalty by leveraging your customer experience data.