Mac: back up to cloud storage or iPod
If you can have both machines for a period of time you can use Migration Assistant to copy your user directory directly from one Mac to the other.

While an iPod can be used as an external disk practically speaking it's an expensive and somewhat delicate mechanism for doing so – iPods get very warm when used as data drives for extended periods. External hard disks are (by most metrics) cheap these days, and will generally be more reliable than the micro hard drive in the iPod.   My first choice for backing up to an external drive is SuperDuper!

I don't know your definition of expensive but for offsite "cloud" storage, I recommend CrashPlan. You can pay for their cloud storage–50 bucks/computer/year for home use–or use the software for free to back up to local drives or drives connected to an offsite computer.

Time Machine has its uses, and is definitely "better than nothing", but I use it for recovery of individual files and prefer these other solutions for transferring data to a new computer.