Real-time GPS tracking

For a while now, I've been looking for good real-time GPS tracking options that work with my Android phone.  I want to use this technology for the following things:

• When I'm away from home, to let my family know where I am.
• If I go running or hiking, to let others follow me online and in real-time.
• For fun and safety while paragliding, also in real-time.

Some criteria that are important to me:

• low battery consumption
• possibility to view everything live in Google Earth
• preferably allow customization of the time between two track points
• ease of use

These are the current solutions that I came across, together with their advantages and disadvantages:

1. Google Latitude: advantage is that it falls back on mobile phone or WiFi networks for the localization if GPS is not available.  Battery consumption seems also ok.
2. Gaggle with LiveTrack24: seems nice for paragliding, but looks a bit overkill for simple running or hiking.  Rumors indicate that it has a high battery consumption...
3. InstaMapper: haven't tested this one yet, but might be an option for running...
4. WiaTrack for GPS-Trace Orange: haven't tested this one yet.

If you have other (preferably Free and Open Source) suggestions, please let me know!