Pretty funny, but I wonder: what is all this obsession with appearing manly enough?
I say onto you: nobody is this modern world is manly, or at least have proof of it. If you don't have to hunt down your dinner and protect your family from sabretoothed tigers, you have not really had your manliness tested. The modern man is soft, live with it. So worrying about whether wearing sandals or a shoulder bag makes you look un-manly is idiotic.
By the way, it seems nobody has caught on yet, but we clearly need a belt clip/case for the iPad. Many professions, like doctors and scientists, are using iPhones, and iPads will be even better for them, so they need a way to carry them around. It's too big for a pocket, so when you don't need to carry anything else (to justify a shoulder bag), a belt clip is the thing.
Update:Some men seem to think that apart from a rucksack or a sports bag there's no option for carrying things which will not make them feminine. I beg to differ, there are so many excellent choices for shoulder bags of all kinds. For example, I have one from Crumbler which is good looking, light weight, strong, and practical (pockets in various sizes and so on).
But there are so many things you "can't do" as a man. For example, notice that you never seen men walking around in pairs. Perhaps for fear of being taken for gay. Girls can walk in pairs, and a man can walk with his girlfriend or his family, or with a group of guys, but never in pairs.