Also for those that just want to few some GPIO pins and not to worry much I have found these Worry free GPIO pins(tm)
If you have need to use just few GPIO pins in your DIY project then use GPIO pins 18, 19, 20, 21, 22 and 23 without any worries, these pins are not used during booting. Other GPIO pins are not suitable for use if you don't know exactly what you are doing because they are used during boot process (bootstrap).