David Bisset

This bare-bones plugin takes activities generated by the BuddyPress members, profile, member, and/or groups components and posted them to your Slack team. You can choose to have this stream of posts go to a particular channel, private group, or even a user on your Slack team. The plugin also can provide an optional “Slack” settings panel for users in their BuddyPress profile which gives them control if they want their activities posted in Slack or not.
In order for this plugin to work you MUST login into your Slack settings and set up an incoming webhook integration in your Slack team. Here’s the quick way to do that.
<ol>
<li>Login as admin of your Slack team and go to https://api.slack.com/incoming-webhooks.</li>
<li>Click the ‘Set up an incoming webhook integration in your Slack team to try it out’ link that is near the top.</li>
<li>Choose a channel (or create a new channel) under “Post To Channel”. Note that this is the default channel and the plugin can override this to post to another channel, group, or user.</li>
<li>You’ll be provided a webhook URL. Grab the provided webhook URL and use that in the plugin settings.</li>
</ol>
Needless to say, without a correct webhook the plugin won’t work.
Please note that if you have a busy site, your Slack channel might fill up quickly. Use responsibility. Don’t do drugs. Stay in school.

BuddySlack

Have BuddyPress activites posted to a Slack channel, private group, or user (via direct messages).

braveryk7

Send Chat Tools is a plugin that allows you to send WordPress announcements to chat tools. 
Currently, it sends an announcement when a comment is received. 
You can instantly check comments that you didn’t notice with the default email notification.

Send Chat Tools

Send Chat Tools is a plugin that allows you to send WordPress announcements to chat tools.

BuddySlack vs Send Chat Tools