Seqwa - Seqwa is a low-cost, easy-to-use hosted search platform.
MailClark - The Slack bot for external communications
Algolia - Algolia's Search API makes it easy to deliver a great search experience in your apps & websites. Algolia Search provides hosted full-text, numerical, faceted and geolocalized search.
PigeonBot - Send emails via Slack with the /email command
Moleskine Smart Notebook - Turn hand-drawn sketches into fully workable vector files
Clubble.io - Answer emails via Slack.