Jumps you straight to your unread messages, then hitting "r" will mark each one as read starting from the top. Easy way to zip through your 'Slack inbox'.
Update your surname with work hours along with a common timezone for everyone.
Example: My name on slack is "Ayush 11am-9pm IST".
I manage a slack for my friend group. My wife and I have a private channel. By far our favourite feature is slacks reminders. We use it to remember to take out the garbage, to read the daily stoic etc.. However, the best use is to remind ourselves monthly to check in with one another, see how the relationship is doing, what we're struggling with, what we're grateful for.
One of favorite Slack Easter eggs: you can change the color of the app on your iPhone by going to Settings > App Icon.

I have a slack team that is all for me and my personal life. All my stuff get integrated into it. It keeps me organized!
Send messages, files and reminders to yourself. Exactly the same as emailing yourself, only faster.
1/ Copy and paste a URL into Slack. 2/ Click on the URL. 3/ Use the modal to write your custom link text. Voila!

We have dozens of channels on the Product Hunt team, most of which I don't need to actively check. As a result, several channels are bold with unread messages creating a visual distraction.
To mark all messages as read in every channel, hit SHIFT+ESC. But be careful, you can't undo it.