Provide a link or two as examples so people can quickly try it out. Make it clickable rather than something they have to copy and paste. Maybe have a grid of popular products for this. This allows people to try your service and also gives them ideas of the types of products they might track.<p>I could see something like this being a really quick way to get alerts when a competitor changes their price. Not sure if there would be legal issues in promoting this though.<p>In the text here ("Enter your email in the field above for future price notifications"), the field is below, not above. At least, it is in my browser.