I started seekeng for geacaches and using CacheMate application as GPS software on my Treo650. If it is always on it consumes lot of power so I tried to reduce power consumption. I found that PalmOS support so called "REM sleep" - LCD is off but all other functions remain on.
I created CM_sleep utility to allow CacheMate stay connected to GPS but lower power consumption from LCD always on. CM_sleep just tracks which application is running and if it is CacheMate it goes into REM sleep when Power-off is required. Application is available here.