First off, jailbreaking is LEGAL. Some of the properties of jailbreaking are not.
So you wan't to jailbreak your iPod? Read internet exploitations 2.0 and get back to me. this is about people who have jailbroken and dunno what to do.
Welcome to jailbreak! First off, you want Cydia and Rock (you need to install rock) Rock is a bit easier to use, but not everything works with it. Many people ask about themes. Themes are installed via Winterboard, and can be altered with the winterboard app. Some themes are installed for you, such as Saurick's packages and stuff. You can get any kind of theme you want really, just as long as it's on Cydia or Rock, I use Glaskart Complete as it is one of the most complete and all encompassing themes there is to offer, boasting 6600+ icons, and tons more extra features. Another great customizable feature is the sounds or UI. These range from Mario, to glad0s to Droid UI (my favorite) These sounds are as simple as start-up, shut-down, charging, email, message
And the best thing? It takes away the click type sound effect! Bonus for me at least. Anyways, winterboard aside, moving on to springboard customization. Many people tend to stick to the 4x4 springboard but I am really fond of the 7x5 dock. But that's just me. You get these simple customizations from an app called Iconocasm, which will run on anything before 4.0. Another disclaimer, some apps will not work past the IO 4.0 update so if you have 3.1.2 or something don't update you're not missing much if you don't. Definitely get the 5 icon dock, it wins. Well, on to sources, I use Sinful.iphonerepo and it works very well for cracked rock/cydia apps, also use cydia.hackulo.us and install installous and appsync plus your firmware. other than that, jailbreaking is up to you. You are the master of your own destiny! SEIZE IT BY THE APPLE! SLAM IT TO THE GROUND! AND SAY I AM JAILBREAK!