webcam work as bar code scanner, connect to our database, and give client a cheaper choice.
ex: client use webcam on his cell phone to scan a bar code on a book in B&N, the cell tell him: on amazon, the book will be 10$ cheaper.
one click, the order is placed.

noise reducer,
use a computer, 2 mic, 1 speaker, and act as an noise reducer,

mic2---speaker---mic1---------------------noise

speaker = 0 - mic1(noise) (the point is...try to make mic2=0);

this one is just thinking...
have a molecular detector(biosensor), which connect to computer, when you input a molecular into computer, the detector can now detect the molecular you entered.
ex: you input H2O, the detector will modify itself, and now it can detect H2O for you. when it detect H2O, it give you a beep.

this one might be usefal

use alignment technique in datamining. ex: align text information, like html code, and get the information we want.
align html code in two web site talking about same content, we can get the most important info from both of them.
align html code in two lyrics web site, weather web site, etc.