Yesterday I met up with Jeff Pulver to discuss some business ideas, and one of the topics we touched on was, “If you could build any iPhone app, what would it be?”

The new iPhone 3G and the imminent release of the App Store have created an amazing amount of buzz and speculation about what the next generation of mobile apps might be.

While I am unable to comment on any of my iPhone development efforts or the details of the iPhone SDK, I thought it might be interesting to ask here as well, “If you could build any iPhone app, what would it be?”

So, simple as that. What is your ideal “killer app” for iPhone? Write your idea here, and maybe we’ll build it!