Can I log into a web application automatically using a users windows logon?
To the best of my knowledge the only browser that automatically passes your login credentials is Internet Explorer.   To enable this feature select "Enable Integrated Windows Authentication" in the advanced Internet options dialog under the security section.  This is usually enabled by default.  
The web server will have to have the Anonymous user permission removed from the web application and enable windows authentication option checked.   Simply add the users you want to have access to the web application to the file/folder permissions. 
I have only tried this with IIS so I'm not sure if it will work on other web servers.
On the intranet at my part time job (not IT related) there are various web applications that we use that do not require logging in explicitly. We are required to login to Windows obviously, and that then authenticates us some how.
I'm wondering how this is done? Without worrying about security TOO much, how would I go about authenticating a user to a web application, utilizing the windows login information? I'd be using Python (and Django). 
Are there limitations on how this can be achieved? For instance, would a specific browser be required? Would the application and intranet backend have to be hosted at the same location or at least have to communicate? Or is it simply getting the users Windows credentials, and passing that to the authentication software of the web application?