Send To Dropbox is a beautiful, simple way to email files to your Dropbox
When you register to Send To Dropbox, it doesn't require your Dropbox username and password. It simply asks permission to hook into Dropbox's API. Once you agree, you get an email address that ends with @sendtodropbox.com. Anything sent to that email address ends up in your Dropbox, sorted according to date, subject, or From address.
You can either give this address to people that you trust, or you can save it for yourself so that you can email things into your own Dropbox. I wish I could create a Gmail filter that would forward emails from a particular person (who always sends me files) so that they would pop right into my Dropbox. Currently, this doesn't seem to be possible because Gmail sends out a confirmation email when you create a filter that forwards email. Since this email doesn't have an attachment, it doesn't show up in your Dropbox, so you have no way to read it and feed Gmail the confirmation code. That's too bad; that could have been a killer feature.
You can also have the service put all of the files under a folder called Attachments, which makes a lot of sense. It can also unzip any ZIP files for you automatically.
When I tested the service, it worked as advertised. This really should have been a Dropbox feature from the get-go, but as things stand now, it's a great demo for what a good coder can do with a worthy API.
The service is totally free. I don't know if there are any size limitations, but I assume that you should be fine as long as you're working in the megabytes (say, up to 20). Kudos, Ralph Holzmann! (And if you could fix that Gmail thing somehow, that would rock.)