Whilst you have the Google document open, if you are logged in to your account, users can (pretty much) see your email address in both the viewer list and the chat area. Even if you are logged in to an account that did not create the document, it is possible for your active account's name to be revealed if you have permission to edit the document with this account. See here for more information.
By looking at File > View revisions... within the Google Docs interface, users can see your first name (regardless of whether or not you have the document open). They can also see a list of all of the first names of the users who have modified the document. Having viewed your document, upon viewing https://docs.google.com/#home I can see your document as well as your first name within what I assume to be a history list.
There may be additional information that could be retrieved, but I am not aware of anything more than what I have explained so far.
Having looked at the HTML of the Dropbox page, I cannot find any trace of your email address, or anything that looks like a user ID. Furthermore, I checked my Dropbox and it seems that the URL cannot be modified to guess the other files in an account purely from a link to one file.
The template for the URLs I was seeing in my own Dropbox is as follows:
https://www.dropbox.com/sh/foo/bar/baz
Where...
foo is a seemingly random string that remains the same for each link for a file within this folder.
bar is a seemingly random string that is changed for each file (even if they're in the same folder).
baz is the file name - the same as you have named your file.
This means that users cannot view the other files within your Dropbox folder without you sharing the direct link to the folder. Note that the layout of your provided Dropbox link seems different. I don't know which route you have taken to come out with such a URL, but what I have said above about the URL might still apply.
With both of your provided links, I haven't any specialist knowledge in the respected areas, so I cannot be sure that there is not more than I have found.
Finally, the following pages might interest you:
https://www.dropbox.com/help/179/en
http://forums.dropbox.com/topic.php?id=52884
The best option is to roll-your-own. There is an opensource option that takes a bit of set-up, but is fairly good and does respect permissions, however, it does require you to generate everything for your clients. In any case - worth checking into:
ownCloud
ownCloud gives you universal access
to your files through a web interface or WebDAV. It also provides a
platform to easily view & sync your contacts, calendars and bookmarks
across all your devices and enables basic editing right on the web.
Installation has minimal server requirements, doesn’t need special
permissions and is quick. ownCloud is extendable via a simple but
powerful API for applications and plugins.
ownCloud started with a keynote by Frank Karlitschek at Camp KDE’10
where he talked about the need of a self-controlled free and open
source cloud.
Best Answer
It is a Firefox settings issue. For Firefox 31.4.0, open the Options Dialog Box and then select the Applications tab. In the Content Type column select Portable Document PDF and then choose the action you desire.