I would like to inform friends / family where I am by if possible posting my GPS location and displaying it on a map. I have heard there are some services that allow this?
The best way to do that on a mobile device is by using WhatsApp to share your location. Whatsapp can be installed on any smart phone (even some feature phones comes with it), click the "send location" button and the other person will receive an accurate location and once click it will automatically open the navigation application. I personally always use Whatsapp when I need to share location. Other messaging applications also offer the same feature but Whatsapp is like a universal app and most people have it.
Anyway, if you want to do it by sharing GPS coordinates in any browser in any device that has a GPS feature, go to MyGeoPosition and it will give you your GPS coordinates. Copy and paste the location and send it using any messaging method and let them use either the same page or any other page/app to reach you.
Google Locations is one way to do it if you want to allow your selected friends and family to see where you are in near real time.
You'll need to have the Google+ app installed on your Android. Start the app and select Locations from the left hand menu. Of course, it requires an internet connection to update your position in real time, which is expensive if you're roaming overseas. However, you can always choose to leaving roaming turned off and it will update whenever you're at a WiFi hotspot.
While you're at it, you can also post a travelog, photos, videos, etc. It's a decent platform for social sharing and with a more configurable privacy setup so you can really choose who sees your stuff.