I've created a set of components and some samples that allow you to upload files using drag and drop and which will give progress notifications as the files upload.(*)
I didn't build a really nice UI for uploading - but what I've done will let you build the sweet UI you would like to have.
Check out the code and a sample at http://uploader.codeslower.com/. Feedback here or on GitHub (https://github.com/m4dc4p/uploader) is greatly appreciated.
Let me emphasize again that I'm not interested in improving the sample UI; I am more interested in improving the underlying components to **make** a great UI.
(*) Of course, IE doesn't support any of the interfaces to make this work, so the UI will fall back to the plain old file-picker.