There are a ton of different OCR formats you can utilize: text, html, word, PDF, etc. Adobe provides an OCR format that gives you the ability to "carry" converted text along with the original image, called Image with Hidden text. This format has the benefit of providing full text search capabilities, but also having the pristine original image. Why use OCR Software?
Lets take for example a SharePoint Scanning application. Utilizing the PDF iFilter, you can enable SharePoint to crawl OCR PDF content, providing end users not only with column based search capabilities, but also with full text search. Here is a link to enabling the PDF iFilter.