Every company attempts to solve a problem. Some problems cause enormous pain. Others do not. For the problem-ridden customer, the product is either a vitamin or pain pill. Unfortunately, many entrepreneurial companies are vitamins, not pain pills.
In my experience in talking with a few hundred people about Glass at SXSW 2013, the immediate application opportunities people think of are vitamins. For example, ChatRoullete for Glass, driving with Glass, finding strangers in a crowd with Glass. Unfortunately, 99% of the ideas people have for Glass are vitamins. And that's true not because the ideas are bad ideas, but because of the nature of Glass itself.
The #1 sales challenge for any application developer that wants to write on the Glass platform is the cost of Glass itself, $1500, especially given that everyone already has iPhones and Androids in their pockets. In order for a Glass application to be successful, the application needs to be a pain pill, not a Vitamin.
As Glass becomes more popular, more novel vitamin applications will spring up. But in the first year the device is on the market, the only successful applications will be those that solve a big problem that iPhones and Androids cannot. I will venture to guess that at least 90% of the successful Glass apps in Glass's first year of availability will be commercial applications. Companies will pay to make their employees more effective and efficient at their jobs.
Glass Developers: please, ignore the silly consumer applications. If you want to do anything on that platform, write something that companies will pay for. In the first year Glass is on the market, consumers won't.