XM Radio Offers Free Trial
Before you get too excited, this isn't a free trial of the hardware based service, it's their online offering. Still the content is virtually identical (buying the hardware based service gets you more channels). Try XM Radio free for 3 days to see if any of the content is something you want to pay $8/month for. Registration is required, but you don't have to give out any credit card info. This is certainly cheaper than buying an XM Radio unit and deciding it wasn't worth the investment.