Unfortunately, there is no way to an ipod without a credit card. The companies that give those rewards need to make money somehow. For people without credit cards, I tell them to go to YouTube and search for terms like "Free Ipod", "NBC", and "CNN". There are news reports on there that prove companies like TRAINN are legit. Show a family member the video and see if they'll let you borrow their card. Maybe then they would feel more comfortable letting you put $10 or so for an offer.
The best way is to sign up for a rewards site, but do some research on them before you do. I was skeptical, especially since my credit card number would be out there, but TRAINN is a very reputable website and has been covered by CNN and NBC as legit. Yes, some of those reward-style sites are legit. Here's the short version of how companies give away "free" stuff. The companies who offer trials pay the company for each offer someone from their site completes. So, when someone does Netflix, Netflix then pays that website money for the referral. The money made more than covers the cost of whatever reward you select. Don't think the companies are being nice, they are making quite a bit of cash from these deals.
Websites will send things like game systems and iPods as rewards. That is true, but what is misleading is the whole "free" aspect. No, it's not 100% free. They couldn't make money if it were. When you sign up, you agree to complete one offer to activate your account. Offers are around $10 on average. From there, you have to find family and friends to be referrals for other offers so you can have them count towards your prize.
Also, beware of people (lots of them around here) that claim they have "hacked" versions of the rewards sites that require no credit card from you. What they give you is a link with their referral number, so you go do an offer thinking you'll get a reward and, shockingly, nothing happens for you. However, their reward just got closer thanks to your referral!
The bottom line is you need to research the sites and determine which is the best site for your needs. Personally, I use sites under TRAINN's umbrella as they seem the easiest to deal with. There are some good groups on Facebook that are made up of users of those sites. A good one in particular is a group called "Shortest TRAINN Conga Line" on Facebook. They offer advice and answers about how the sites work and tactics to get stuff quickly. You can also get in the Conga Line for easy referrals