SearchBlox supports a field called click_count which records the user clicks made to the search results. Based on this value there is a tune parameter tune.6 in the search which would increase the relevance of the documents that have high click_count i.e., viewed most times when compared to other documents.
By default, this tune.6 parameter is given a value 10 which naturally increases the relevance of documents with click_count. If you need more weightage to be given for viewed documents you can increase this count.
Please note that this will not work if you disable tuning.
To learn more on relevancy tuning read: Relevancy Tuning in SearchBlox