We all know how important the killer app can be. In the computing world, it can make or break a new emergent technology. PCs had Lotus 1-2-3, Apple had Adobe, but what will the phones have? What's interesting about killer applications in the past is that they served a unique niche market with almost completely proprietary solutions. But when you talk about new world computing. You seldom hear of the answer to a new question. Until we stumble on the next major technological discovery period, we're working on improving designs and plans for existing technologies.
You may be thinking, "how will I know when I see it". It's pretty safe to say that the mobile phone's killer app is going involve a number of different existing applications. Mobility is the end game in personal computing. Having developed the computer and then the phone, the marriage of the two is more than just the sum of the parts. Identifying the next killer app will involve identifying components which were primarily unique to the mobile phone AND personal computing. The bottom line is that consumers want information. Providing information which could be found by using a pc is not sufficient for a mobile device.
In order to develop the next KILLER APPLICATION for mobile phones, developers must be aware of the the information that consumers require, and identifying the mobile features (calling, gps, etc.) which can further enable and facilitate the consumer's experience.
It's not enough to lead the horse to water anymore, now the horse expects to be told where the water is closest, coldest, and cheapest. But once that consumer has had a taste and is content, I promise he'll never doubt his killer application again.