MobileMe trials require a credit card

I thought I'd take a look, but I'm not ready to provide a credit card ...

MobileMe Signup

....A credit card is required to start your free trial. After your trial ends, your card will be charged an annual subscription fee of $99.00. Don't worry, you can cancel your subscription online at any time during the trial...

Too big a chance I'd forget and be enrolled with whatever test ID I use.

One acceptable reason for this policy would be to reduce spammer abuse.