> I'd like to see some simple one-time-use password option.

I also agree with this. But I think the "delete once files are downloaded" kinda fulfills this. It does become insecure if someone else accesses it first, but then you know that someone else downloaded the data, right?

For the multiple sharing I think a password would be a really nice feature. You could have that done on the user side, but a good password implementation would be awesome.