XScaleMonitor is a small utility that continuosly shows:
Memory percentage used.
It has three small lines in the top of the screen.
The first one shows the instantaneous processor use percentage, and it's colour shows the speed at what it is running in hundreds of MHz.
The second One shows the battery charge state, and it's colour the current consumption in hundreds of mA.
The third one shows the free memory percentage from the one assigned to run programs, and it's colour the number of 8MB free blocks.