2. A computer implemented method as in claim 1 wherein identifying which keywords commonly occur together in the same user profiles further includes computing the frequency with which a keyword appears in conjunction with another keyword in at least a portion of the plurality of web-based user profiles.
2. A computer implemented method as in claim 1 wherein identifying which keywords commonly occur together in the same user profiles further includes computing the frequency with which a keyword appears in conjunction with another keyword in at least a portion of the plurality of web-based user profiles. 3. A computer implemented method as in claim 2 wherein computing the frequency with which a keyword appears in conjunction with another keyword in at least a portion of the plurality of web-based user profiles further includes: computing the degree to which the two keywords tend to occur together; determining a ratio indicating the frequency with which the two keywords appear together; and determining a correlation index indicating the likelihood that users interested in one of the keywords will be interested in the other keyword, as compared to an average profile.