In a world as globalized as ours, it's hard to believe that there are drool-worthy products out there that you can't buy at the mall downtown, or anywhere in the country. But they exist.

Take Coke. Sure, you can get a regular bottle of Coke (KO) at your corner shop, but you can’t get Mexican Coke, which is sweetened with cane sugar instead of high fructose corn syrup. Sample the cola during a Los Cabos vacation, and you might find you never want to return to
your inferior domestic version.

In the US, shoppers can buy Preparation H (WYE) for certain problems. But in Canada, women rave about the hemorrhoid medicine’s merits as an anti-wrinkle cream. Americans did, too, until 1995, when the Food and Drug Administration banned the key ingredient for that purpose, the
live yeast cell derivative Bio-Dyne.

Whether it’s an environmental regulation, a food or drug policy, or a highway safety rule -- or just plain old lawyers, marketers, and accountants -- many forces conspire to keep some things off the shelves in local stores.

Of course, there are times when products introduced overseas garner so much attention from abroad that its manufacturers have no choice but to answer the market’s demands.

The Swedish clothing chain H&M was coveted by American travelers for years before the store first landed in Manhattan in 2000. Its second shop outside Europe opened in Toronto in 2004. The British fashion chain Topshop just opened its first US store in New York earlier this year after its popularity reached global proportions. Rumor has it that Canada will get its own store, a flagship shop in Toronto, in early 2010.

Other products and services coveted by North Americans aren't offered here simply because it’s not technologically possible. Frustrated iPhone (AAPL) users in the US have relentlessly complained that they can’t tether their devices like customers outside the country can. AT&T (T), the iPhone’s exclusive carrier in the US, promises that feature will come but says it’s not ready yet. (See also: Why iPhone Sales in China Are Stronger Than Apple Thinks)

North Americans have never been shy about making their demands known, and marketers are smart to satisfy them. But rules are rules, so there are times when they'll never be met.

The Peruvian tea called KDrink packs a punch and claims to have weight-reducing properties, but Americans will likely never see it available on their supermarket shelves in its current form. It’s made with a small amount of coca leaves, the main ingredient in cocaine.

Domestic automakers are scrambling to develop electric cars, even though the biggest maker of them doesn’t yet sell them in Canada or the US. The tiny, golf cart-like cars made by the Indian manufacturer Reva are a hit in Asia and Latin America, but safety concerns and capacity constraints have kept it from entering the North American market -- so far, anyway.

Click below to see a slideshow of many more foreign products worthy of our envy.