How to optimize energy consumption during GPS tracking? Very often I use my phone and the app MyTracks or GPSTrackerLite to track my hiking/biking tours.

This really works great and I'm thrilledy by the lot of possibilities in combination with google maps, facebook etc.

However there is one problem: If I'm tracking the battery lasts only a few hours. This is enough for most hikes, but for daytrips, it isn't sufficient. Do you have any tips how to save energy? For example using plane mode? Would this decrease the energy consumption? Are there any other functions I could disable?

I'm using HTC Desire.
See my answer here on some ways to save battery power on your  phone.