It is true that I use a fullblown "desktop replacement" laptop that has 3 wifi antennae in it. My iPod doesn't get anywhere near the range. That's a pretty crap McDs though if you're not getting an ok signal somewhere in the parking lot. I've been able to get one in 95% of McDs I've been to. One important point though, is you need to park in sight of the glass in the front of the restaurant. Concrete walls are blockers. So around the back where people are taking orders at the drive by menu, is not going to work. I'm cheeky enough that I will drive around a McD parking lot first, proving I can get a signal somewhere, before even considering paying for food. 'Cuz if I walk in, buy cheezeburgers I didn't entirely need, then walk out and find I've got no wifi for having paid the 'rent', I'm a pretty big chump right? Well except that I've stolen so much wifi from McDs that I sorta owe 'em, but still, I mostly hold to the principle of "paying for performance".
I once spent a week trying to make a wifi antenna booster for an apartment complex I lived in. Lotsa cutting of precise parabolas and aluminum foil and cardboard and measurements etc. Scaled up a big model too using a plastic box and the stand for a DirecTV antenna. None of it mattered. My complex had a lot of forests, and the water in trees does block signals. Probably I had no useful lines of sight along which to get a boost. I didn't experiment with my equipment by "war driving" because I didn't have a need for that sort of thing at the time, I was trying to get wifi into my apartment.
I did not build a serious hardcore cylindrical correct waveform distance spaced "war driving" antenna. That's what I'd try if I was going to make another go at it.