Tim Krause just turned me on to a (fairly) new tool that is pretty convenient for sending large files to multiple users (e.g., turning in a dissertation, submitting a book, etc. (-:). It's called Drop.io:
You can drop files (and even voice messages) via the Web, phone, email, or widget. Free for 100 MB. Not bad! For 1 GB, you can pay $10/year.
Dave



just used drop.io
I have just finished sending audio comments to my online students using drop.io. Worked great. I have not tried the commenting and collaboration features yet.