Equipment

iBook

Unfortunately, the iBook doesn't have an external Antenna slot built into it. However, the iBooks do naturally have a great range because of there design and the materials they have been made out of. (The powerbook's wireless range is nothing compared to the iBooks, partly because they are built out of metal). But don't worry, there are a few ways to add an antenna to your iBook.
Here they are:

1st Method:
This method is risk free of damaging your precious iBook. All you need to do is buy a USB wifi card/dongle and then build a cantenna for it!
Click here for the full tutorial with pictures!

2nd Method:
This is the only way to safely add an external antenna to your iBooks built in Airport or Airport Express Card. This method requires firstly a little bit of determination and confidence as you will have to lift the keyboard to get access to the Airport Card. It sounds a lot harder than it really is.
(This tutorial requires a built-in wireless Airport Card)
Click here for the full tutorial with pictures!

I have also heard of people drilling holes and such into the iBook to reach the Airport card, but i do not recommend trying this.