True Volume

I have no idea how loud my headphones are. Are they too loud? Considering that you don't get a second chance at ears if you mess them up, I'd like to know. The app could have a way to select the headphones you use, and it would tell you the decibel range you were working with. That way, when you're on a plane (or somewhere else it's loud), you don't just crank your headphones up and wonder why your ears are ringing when you land (like I do).

Sennheiser HD 650: less deafness (I think that's literally the only benefit)

Nike Vapor: Just by conceiving of this idea - I aged considerably, teens would think limiting their right to destroy their eardrums "totally sucks."

Dapper App

This idea was originally for color blind people, but would probably be good for anyone. You take a picture with your smartphone of the shirt/pants/whatever you want to wear. The phone identifies the color (or dominant color) and tells you what it is. Then it can either show you (on the screen) or identify (through more pictures) appropriate matching colors. You make this style conscientious, and have various settings (male/female, season, style by celebrity, formal/informal, city... etc.) that would help make you a better dresser.

neat: helps everyone look better, might be popular enough to get into a magazine and sell a billion copies to tweens

OCD: might have trouble with stripes, lighting, etc; might cause more awkward wearing of the same thing in middle schools

Wilderness ID

Whenever I go hiking I always ask or guess which mountains are which. There should be an app for that. I know that smart phones can tell which way they are pointing now, so I think most of the work would be in programming. The app should identify mountains and landscape features, so you know what it is you're looking at.

bald eagle: fun, worth about a dollar, if you use it to memorize where everything is you can impress your less knowledgeable friends with their dorky dependence on their phones

baldness: you can just bring a map, it would be annoying to find people all on the top of a mountain with their phones out - waving them around, ugh.

Stoplight App

So everyone I know uses their smartphone while driving. When stopped at a stoplight, they text, surf the internet, etc. Generally, they don't know when the light changes. There should be an app for that. The display would show you the color of the light you're sitting at in the corner of your tiny screen, and perhaps buzz when it changes.

barcelona: helpful, common, worth about a dollar

real madrid: i have no idea if traffic light data is public, and if so, who and how you control it