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.
Norbert is an intelligent lead generation tool that can find anyone's corporate email address and enrich it with data that drives conversion.
It won't blow you away but the accuracy is pretty good, and it has a clean user interface. It's one of the few platforms that doesn't require a subscription - you just pay for however many emails it finds.