I have a deep background thread running in my head that started when I read in The Year Without Pants: WordPress.com and the Future of Work about how Automattic, Inc. created a new Wordpress site for every bug. I tend to think of blogs as having weight. They are heavy. However, this is psychological response to how blogs have been used. Technically, they are not much more than a column value in a database table. One of the lightest datum there is. Slack is no different in this regard than is Wordpress; Slack's Workspace is no more than a column value in a table.
Recently, I had the idea that you could use a private Slack site for personal projects and journals. Each channel is a new project or a journal. Slack's chronologically organized messages allow for text, images, (simple) formatting, and the inline inclusion of external content such as from Google Apps. There are many bots for managing each project's actions and reminders, for example. And if you do need to share the project you can. As I thought about this more there seemed no end to how to use Slack as purely a personal information tool rather than a group communications tool. I wonder if anyone has actually used Slack this way?