Examples of this include things such as instant messaging (IM) and team chat tools, video conferencing software, online meeting collaboration tools, shared team intranet sites, and more. Some even integrate with third-party tools such as Slack, a highly popular collaboration tool that combines customizable chat "channels" with file sharing and project management. For those who want to integrate with certain apps more deeply or integrate with custom-developed apps they have built in-house, many bigger-name email services will provide robust application programming interfaces (APIs) that will let your in-house developers or consultants deliver on those needs. They will need to be involved in the email service selection process, however, as this is an important consideration during your evaluation period.
You can also purchase Secure Sockets Layer certificates (starting at $69.99 per year), the software that's represented by a green padlock in your web browser when you visit, say, a financial institution's website. If you plan to sell products via your website, consider an SSL certificate an essential purchase, as it safeguards the data exchange between a customer and your servers.