- “Next Discussions” is based on card titles
- “Next Version” is based on card titles
- “Telegram” is tagged
- “Building and Construction” is a lot of different filters: tags, parents, author, perms, etc
- “Unchecked” is just the “Tasks” default collection, renamed (so a content filter)
And don’t want to answer for him, but @freisatz actually posted about his “Serendipity” collection here. In essence, it is a collection of all cards with the “random” sort enabled to help with rediscovering cards that haven’t been seen in a while.
Which is honestly such a good idea we’re considering adding it (or something similar) as one of the pre-configured defaults.