Similar to the Amazon system of 'was this review helpful.' As many reviews are pretty much a listing of positions, they are not very helpful in determining the personality of the provider, which helps in selecting which provider would be a good match.

By allowing others to rank reviews in terms of helpfulness, we could easily read those reviews that would be most helpful for the selection process. Of, course, all reviews would still be listed in their chronological order as well.

-tessen