Domainz.io - Premium domains, for not so premium prices
Listmonk - Send e-mail campaigns from a powerful dashboard. High performance and features packed into one app.
Park.io - The best place to backorder/drop purchase expiring ccTLD domain names.
Sendy - Sendy is a self hosted newsletter app that sends emails 100x cheaper via Amazon SES
estibot - Domain name valuation
Hiver - Manage Customer Support, Sales and Projects right from your Gmail inbox. Collaborate with Shared Labels, Shared Contacts, email notes, email reminders and email templates