Inspired by the CPU meter posted by blair1618, Vanglad posted the code for this RAM Meter in the comments. The code didn't display very well, so here's a downloadable .glet file that you can use instead.
myRAM=`top -l 1 -F -R | awk '/PhysMem/ {print "" $8+0}'`
totalRAM=2048
myPercentRAM=`expr $myRAM \* 100 / $totalRAM`
declare -i a=5
while [ $a -lt $myPercentRAM ]
do
echo "|\c"
a=`expr $a + 5`
done
echo "\033[1;31m|\033[0m\c"
while [ $a -lt 100 ]
do
echo "\033[1;30m|\033[0m\c"
a=`expr $a + 5`
done
echo "\n"
unset myRAM
unset myPercentRAM
unset a
