4
You don't need to do anything. Recent PDAs (well, pocket pcs using 2003 and above anyway) have a pretty good browser that can reformat webpages for display on a small screen. Pages (can be) 'sliced' into columns so you can see the whole site by scrolling up and down. There's a few different viewing options.
However, there *is* a PDA-friendly theme available if you want it (don't ask me what its called, have a search). The same guy also made a 'phone friendly' module.
The simplest way to make a page PDA-friendly though is to make it single column only, and don't use wide pictures or fixed-width objects (particularly in your horizontal menus).
Making things display nicely on a mobile phone is a far more difficult issue (but hey, only maniacs look at the web on their phone).
