I was going to request a "Tags" field type, then I stumbled across it. Already exists. Cool.
Now here's one way I'd like to use this. I currently keep track of my daily team meeting agenda in a text editor. What would be much cooler: if I could flag any item in SG--a note, a task, etc.--with the "agenda" tag. That way I could constantly building tomorrow's meeting agenda throughout the day. Very handy.
What prevents me from doing this is that I cannot build a single view that aggregates different types of entities on one page. So yes, I am backing into the old "flexible Dashboard view" feature request. Instead of widgets however, I would imagine this as a more standard list view, listing entries from different entities on a single page.
This would be a challenge since different entities have different fields. But you could at least display a "primary key" (code) column, along with common fields, such as "Description" or "Status", which could conceivably co-exist in a single table.