Unless you are lucky enough to be in a blue ocean market, there surely are people who have built products similar to yours before you and who have failed.

But before they went out of business, chances are they've managed to get their product talked about, whether in blogs, tool directories or in the press.

You can take advantage of this quite easily by making a list of all your competitors that no longer exist and search for websites that mention them.

All you have to do then is to get in touch with the author to warn them that the product they mention no longer exists and that they can replace it with your product.