There are actually two methods we are going to highlight that both of which give good results, neither of which are the definitive tools for the job (the Windows-Mobile-as-iPhone community is surprisingly active). One method is relatively simple, the other requires a little more legwork.
Add a 100GB Toshiba hard drive to spice up your Zen with more room. Obviously this will void the waranty, but you will have the largest drive in any Zen W in the world.
HandBrake is a GPLd multi-platform, multithreaded DVD to MPEG-4 ripper/converter - it is super easy to rip the DVDs you have and put them on the new iPhone - they look great and are about 1 GB each, here is how.
This has VGA out, Serial port with circuit for TTL to RS232 signals conversion. Car charger Input for 5v Dell power supply PDA USB client connector. USB HUB x4 Audio preamplifier with double format output RCA and mini-jack connectors.
For around 30 dollar in parts and a good amount of patience, you can have a completely open source and hackable mp3 player ready to go. It can be modified to accept serial commands, be embedded in an art project, used as the voice of your next smart talking robo-sidekick, or filled with music and used as is.
Although it is hardly the most visually appealing device modification we have ever seen, the practicality that this do-it-all dock offers Dell Axim PDA owners is pretty much unrivaled.
Want to use XBOX game controller when playing games on PC? The author will show you one of the most popular XBOX mods.
Nintendo Gameboy sized toy, designed around a pirate NES chip with onboard games. A 2.5 inch color screen and original NES controller were wired up to create a portable NES with approximately 50 popular games built in and 6+ hour runtime on 4 AA batteries.
Docking cradles are more convenient if you connect your ipod frequently, but apple charges way too much for them. The ipod nano is especially easy to make a cradle for because it comes with a plastic insert to make it fit larger docks. With this, a cable, and some Plexiglas you can make a dock.
This page has instructions for building your own serial cable that connects directly to the PS2's EE processor. It only needs 5 wires soldered onto the PS2 mainboard, and a simple interface circuit to convert the EE's voltage levels to the standard RS232 levels.