monitorThis started as a mini-project in 2007. At that time, it was a form on a page with an input field where you could enter a search term. monitorThis then scanned RSS feeds from well-known search engines and blog directories and returned an OPML file, which you could then import into your RSS reader. This way, the term you wanted to monitor on the WWW was available in the RSS reader. If you updated your RSS feeds, you would get the new search results for this term.
It was actually just a small side project, because I wanted to try this new AJAX thing at that time. After this, monitorThis was lying around somewhere in a subdirectory on my domain. I had blogged about it once. But with time many people discovered this tool and more and more links to it appeared in my website analytics. So many that this little AJAX experiment became the most popular URL on my server. People put the tool in the category "reputation management", a term I had never heard before.
After 3 years I decided to make more out of it. A colleague helped me with the backend work and made sure that the results were cached on the server. The results were now, similar to a search engine, displayed as search results in a page. We kept the possibility of the OPML export, however.
This new version also got so many users that I soon had to decide: either monetize or give up (because because the server costs increased more and more). I would have liked to do the former, but my private circumstances did not allow it at that time. So I gave up the project.