I stumbled upon FileChute
This looks like a really nice alternative way of attaching files to e-mail. Instead, it would appear FileChute uploads the file to some online account you may already have, and includes a URL reference to that file in an email you're composing.
I really really like this idea. In fact, EarthLink should integrate such a feature in their software.
I've just downloaded and tried it with my EarthLink account, and it worked very well: Upon launching the application, you are greeted by a welcome screen. At the bottom of that screen, click set-up. Choose the type of account, in my case, "EarthLink". Enter the username and password, and you're done.
What you'll likely want to do is drag FileChute's icon to your Dock. After having set-up the application, I was trying to drag files anywhere in that window, and it wouldn't do anything, a minor usability gripe the authors might want to address.
From this point, you can drag any file to the FileChute icon. This will compress and "copy" the file onto your online storage, in my case, my EarthLink FTP account. You can then control-click, or right-click on the "link box", to compose an email with a link to the file you've just placed online.
This is really quite cool.