The guys at SmartReach.io have created a pretty cool plugin for LinkedIn and Gmail. Find contact details while browsing LinkedIn, or directly within gmail as you are composing a new message.
We think the Gmail email finding feature is pretty cool, and definitely unique. If you use Gmail a lot, and outreach to many people on a case-by-case basis, we'd recommend it!
EmailSearch.io is a simple tool that allows users to search for email addresses based on domain, LinkedIn profile, or company.
They have have a CSV upload and API solution for bulk email searches. Upload your document and have it enriched with contact data in no time!