Puts a "zram" (compressed memory based) swap on a machine. Works at least in some recent debian based distros, maybe others too. Script was made for debian (raspbian) wheezy. Stuff that gets put in the zram swap usually compresses quite well

zram.sh

#!/bin/sh
FILE=/etc/rc.local
grep -q enable_zram $FILE && echo Zram already enabled && exit 1
#remove the exit 0 line. Hopefully it's the last line.
sed -i -e "/^exit 0/ d" $FILE
cat >>$FILE <<END
#enable_zram
modprobe zram
#a good size is about 10-20% of physical ram.
echo 52428800 > /sys/block/zram0/disksize
mkswap /dev/zram0
swapon /dev/zram0 -p 10
exit 0
END