Adapt is a B2B contact and company database provider across multiple industries. Adapt has 100 million business contacts, including industry-specific company database and contact information such as job title, direct dial, and email addresses.
It's affordable and they seem to be able to find a wide range of contact details. They have a nice Chrome extension which works well.
Lead411 provides comprehensive and accurate information about contacts and companies available in the marketplace. They have over 450M contacts, within 20M companies worldwide. Through targeted filters, and sales intelligence data points, customers are able to view complete contact data profiles and find growing companies that are more likely to be in a buying cycle for adding services/solutions.
Their CRM integration is seamless, and this makes a huge difference if you are regularly importing leads.