@Bkai, if you have NZBDrone setup on a linux machine running apache2 you could create a proxy for the calender which I did. You would use base64 authentication on your username/pass so no login is needed on the proxy.
Here is how:
Navigate to /etc/apache2/sites-available/
Edit the file 'default' (with nano or something like that, need sudo rights)
Just before the </VirtualHost> you can add the following:
@[nzbdroneport] = Enter the port of your nzbdrone setup
@[basickey] = Enter user:password encrypted with base64, use a site like this and input user:pass. This will give you a string looking somewhat like this: dXNlcjpwYXNz

After completing these steps you can go ahead and add http://[yourip/hostname]/calender/NzbDrone.ics into google.

NOTE: You can change the Location /[foldername] to anything you'd like!

Thanks guy.. that will help me reverse engineer for nginx as well. I should be able to whip something up for that!

LJ

Very odd. I got it working via nginx but it refuses to display information in google calendar... =p

Thought I'd post the nginx config I'm using if someone else wants to try it as well!

location /calendar {
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Authorization '';
proxy_pass http://192.168.1.5:8989/feed/calendar;
proxy_set_header Authorization 'Basic asdf=';
}

Google calender doesnt update instantly! Be warned, it imports the data once every few hours so be patient.

ah.. that explains it. Google hates self-signed certs too... *shock*