Hi,
A successful site is one that ranks high enough for its chosen search
terms that it gets sufficient visitors to achieve the objective that you
had in setting up the site in the first place.
silvermoon
I agree ldcdc that it is complete up to the websites owner as to what constitutes a good ranking. To me a good ranking is one that brings me enough visitors to make a profit.
There's no fixed standard to determine search engine success as it is defined differently by each individual. Getting site listed under the keywords that are being used to find sites is a major success.