This probably shouldn't be called a "shopping cart" but that is the pattern that it emulates that we are all most familiar with.

Users have expressed to me that they would like to be able to "Select" or "Chose" individual files to be added to a list that can then be downloaded together.  The download would be basically the same as downloading a Dataset, except a dataset gives you all the files within in it, while this would let you choose a subset of selected files to include.

The expectation is that you could also choose files from multiple datasets or even multiple spaces and download them all in one action.

Like a typical shopping cart, if you didn't "purchase" (read download) then it would remember your cart and leave the items in there.

Typically shopping cart behavior should be included.

That's about it. Nothing too crazy, but could be pretty useful.