I wrote a little handy script that help me a lot when needing a new mac fast on my n900 (its just bash so it works on every linux dist that names their vlan interface wlan0):

Create a file in /usr/bin/ called macchanger, make it executable:
chmod +x /usr/bin/macchanger
edit /usr/bin/macchanger and insert this text:

#!/bin/bash
echo "they block my mac"
ifconfig wlan0 down
ole=`ifconfig wlan0|grep HWaddr|awk '{print $5}'`
one=`df |md5sum |awk '{print }'|grep -o ..`
two=`free |md5sum |grep -o ..`
thr=`ps auxww |md5sum |grep -o ..`
ifconfig wlan0 hw ether 00:1FF:`echo $one`:`echo $two`:`echo $thr`
new=`ifconfig wlan0|grep HWaddr|awk '{print $5}'`
ifconfig wlan0 up
echo $ole "->" $new
echo "i fist their fish"

Reason i am using 3 strings md5sumed is to get decent randomization as this is hard to accomplish in bash