Skype for Slack - Move your slack discussions to a group skype call
Mailjoy - Delightfully easy direct mail marketing. A DIY direct mail tool created for marketing and growth teams. Design, mail & track personalized direct mail postcards and letters. Digital marketers use Mailjoy to send data-driven mail campaigns.
Calls on Slack - Make voice calls in Slack
I hate mailto - Stop websites from opening your email client.
Pingly - Your communication hub — Email, text & voice in one app
The Simple Postcard - Text a photo to mail it as a postcard