Being a computer geek, and super paranoid, I've fiddled around with some ideas until I think I've been able to come up with something that pretty much keeps me free and clear in the "computer tracking" dept. I just thought I'd share it here, so that others can take what they want from it and hopefully help them out.
Rule #1 : everything in cash. If you have to filter some out of the ATM every so often to get a pile together, then that's fine. Cash is king, and basically untraceable.
With the advent of pre-paid cell phones, there are also several services that provide pre-paid internet access. I know of several from Verizon (which seems to be the best quality, but that's just my opinion), T-Mobile, AT&T, and I think Sprint will have one soon, but don't quote me on that. Get a USB-based pre-paid internet modem like Verizon's MC760, and get the monthly package. I got mine from a corner multi-reseller and paid cash for it, giving a false name for the sales reciept. Initially it will have a 500mb transfer limit, but as long as you're not surfing YouTube or downloading MP3s, that will last you a while for basic email and website perusing. Just like cell phones, it can be refilled by buying a pre-paid card (with cash) and applying the balance to your account via phone/acct number.
So now you've got an unconnected IP address that does not have your name on it anywhere. Now for the actual computer tracks...
With this same USB modem, get a MicroSD card (4 gb is fairly standard and cheap) that plugs into it as added storage. If the modem you buy doesn't support MicroSD, then simply buy a seperate USB flash drive.
Www.portableapps.com has a host of applications that will run only off the USB drive, and will leave whatever computer you happen to be on virtually clean. I use FireFox Portable, with an encrypted RoboForm to remember all my passwords. The cache runs from the USB, so no "temp" files are left on the host machine. It's a bit slower, but it's worth the peace of mind. I've also got an encrypted lock on the drive, in case I lose it, all my info will be secured. All these apps run directly from the USB, so there's no trace on the host computer.
When it's all said and done, for good measure simply run CCleaner (again, save the program on your USB) to wipe away any leftovers.
That being said, the rest is common sense. NEVER browse hobby sites/info when you're on a work computer, even using this method. You never know what kind of monitoring is happening on a work computer. Someone could be watching everything on your screen from the other side of the building, and you'll never know. ONLY browse from a machine you feel/know is already relatively safe.
All in all, I've got less than $200 invested in my setup, and that's including the first month of internet service (at $50 + tax). Unless someone walks in on my while i'm in the middle of something, no one will be able to find anything on this computer, nor can my IP address be traced to me. They might be able to see which cell tower I'm running off of, but unless they invest in a full team to triangulate my position (and god help us all if they get that desperate to hunt down us sinners), then I'm less than a needle in a haystack.
As usual (well, not really, seeing as how this is the first post i've made like this), I make full disclaimer that the information included herein is to be used for educational purposes only, and not for any illegal or illicit activities. If you get busted, it's your own damn fault.
Really, this is just one man's idea of how to be safe in the dangerous underworld of computer paranoia.
Peace out.