What are some alternatives?
When comparing Pingpad for Slack and Sharepoint Online, you can also consider the following products
Ryver - Ryver provides all of your team communications in one place: chats, posts, and files.
MS SharePoint - Share, organize, and discover information with Microsoft SharePoint. Learn about SharePoint Online, OneDrive for Business, and Apps for SharePoint
Podio - Podio is the online work platform. Manage, share, and get your work done smarter together with tools that work like you. Free for 10 Users.
Huddle - Huddle | The Enterprise Content Collaboration Platform
Conceptboard - Instant Whiteboards for Teams & Projects
Amazon WorkSpaces - Amazon WorkSpaces is a managed desktop computing service in the cloud.