The revent Essential Scratch and Sniff Guide to Becoming a Wine Expert has become a hot book among wine lovers and future wine lovers using an old technology -- scratch 'n sniff -- to reach a new audience: drinking adults.

While scratch 'n sniff has been around for years, it has never made its way into the adult arena before. The basics of many smell technologies have actually existed for decades (remember Smell-O-Vision?), but they have traditionally been seen as jokes or oddities. They also generally were plagued with problems. Replicating the exact smell of something can be surprisingly challenging and getting it into a product that truly appeals to people can be even more difficult.

It's only been in recent years, as digital technology has become easier to use and more advanced, that smell tech has really begun to go mainstream. This April, the Digital Olfaction Society held its first-ever world congress, according to GigaOM, to discuss and share ideas about digital smells.

At the congress, groups showed off things like the Virtual Ice Cream Shop, where the smells of ice cream mixed with musical notes representing flavors, and the Meta Cookie from researchers at the University of Tokyo, which uses smells and a visor to trick your brain into thinking the cookie you're eating is something else entirely.

At least two companies, both from Japan, are looking to go a step further. Scentee and ChatPerf have invented attachments for your phone that emit scents.

You can replace the cartridges in the attachment to change the smells. Scentee also has an app programmed with three smells: short ribs, grilled beef and buttered potatoes. They seem to suggest the smell can be a substitute if you can't buy food. Of course, you could probably buy food if you stopped buying iPhones.

According to NPR, we'll be able to buy Scentee by the end of the month for $35 for the attachment. ChatPerf was supposed to be commercially available this summer, but is still in pre-order stages. Scentee is reportedly also in talks to create scented ads for advertisers and will be releasing a series of apps linking different smells to your alarm clock, social networks and text messages. Why wake up to fresh bacon, when you could just wake up to the smell of fresh bacon?

Advertisers have actually been trying to figure out how to capitalize on smell technologies for years. Mars has tried to spread the smell of chocolate around its M&M retail stores and Verizon has had units wafting chocolate scent for LG Chocolate phones. The question for them has always been how to make the smell effective and cost-effective.

Wafting scents through the air to convince you subconsciously to buy something is a trick hotels and casinos long ago perfected. Now, everyone else is starting to get on board.

If they can make it effective and cost-effective, Smell-O-Vision might even be coming back. According to CNET, Japanese researchers have also developed a screen that emits smells corresponding with what's on the screen. That could be really appealing -- watching a scene from Julie & Julia would take on a whole new level of tastiness -- or it could be really unappealing. I don't know that I need the smells that might come with CSI.

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