I have a terminal (WidgetTerm) residing in Dashboard, I think it's damn useful to get to terminal just by pressing a key.
I also have a command-line calculator, a Pastebin widget, a calendar, a currency converter, a numeric base converter, SVN notifiers and volume ejector (so I don't have to open Finder).
I wish there was a way to dock regular windows to the Dashboard, though. Most of the Google search results are about doing the reverse moving the Dashboard to the desktop, like in Windows 7. Why the heck would I do that?
Unfortunately the Dashboard is clearly a feature that the average user doesn't need, or the one come from Windows doesn't expect. I'd hate to rely on crappy third-party solutions if Apple removes the Dashboard.