I know the nutrition facts about almost every item on the McD's menu by heart because my sister and her husband own our local McD's. My sister and I train together, so she's very health-conscious, and she keeps me abreast of what's good and bad on the menu. So if that's all you have to choose from (and it often is on the highway, I know), there are things you can eat there.
The grilled chicken snack wraps are 260 calories apiece (270 for the ranch), and I usually get one of those with a sugar free vanilla iced coffee (90 calories) for lunch if I'm running late for work. If I have time to sit, the grilled chicken southwest salad is awesome and comes in at around 300 calories. Good salads from McDonald's, who'd have thought? Also on the 'good' list for me: the fruit and yogurt parfait. It's 130 calories (160 with the granola, which I never eat) and has some protein and calcium.
If you really want a sweet fix, order a plain sundae. It's low-fat ice cream and without the topping comes in at around 200 calories. The shakes are horrible.
Stay away from the shakes. The apple dippers are yummy, but keep in mind that the caramel dipping sauce has 70 calories, bringing your 35 calories of apples up to over 100. Still not bad, if you're looking for a snack, but there's no protein so I'd probably use my 100+ calories on a fruit and yogurt parfait instead.
Surprising facts: The grilled chicken sandwich has more calories than a hamburger. It's that damn bun they serve it on; it's ridiculous. So if you want a sandwich, stick with a hamburger or ask for the grilled chicken on a regular bun. They shouldn't have a problem with that. Just avoid the fries, of course!
I totally just did a McDonald's commercial, didn't I? And I don't even eat there more than like once a month. To be honest, Subway's my first choice when I have to eat fast food. Just don't tell my sister.