Things that most actual Kanban flows have that no one has built into a decent product[0]:
- Nested columns in lanes
- Rows for class-of-service
- WIP limits (per lane, per column, and per class-of-service)
- Sub-boards for meta issues
The actual content of each work item is the least important part of Kanban; it could be a hyperlink for all I care. Kanban is about managing the flow, not managing the work.[0] Please prove me wrong if there is such a product out there!