9. An article of manufacture comprising at least one data storage device having one or more computer programs stored thereon and operable on one or more computing systems to: normalize a plurality of keywords received from a source, the source being from the group: a search query and a product listing; filter the normalized plurality of keywords against one or more keyword filtration lists; produce site-specific variants of the filtered plurality of keywords; associate a plurality of levels of dimension data with each of the plurality of keywords, the plurality of levels of dimension data including information indicative of a probability that a keyword of the plurality of keywords belongs to a particular product category in a product category hierarchy, the plurality of levels of dimension data including keyword clustering dimension data, the keyword clustering dimension data including information indicative of a probability that a keyword of the plurality of keywords belongs to a particular keyword cluster of a plurality of pre-defined keyword clusters, the plurality of levels of dimension data including keyword traffic dimension data, the keyword traffic dimension data including information indicative of a probability that a keyword of the plurality of keywords was trafficked by a particular search engine, wherein the probability that a keyword of the plurality of keywords was trafficked by a particular search engine is maintained for each of a plurality of search engines, the keyword traffic dimension data including information indicative of a probability that a keyword of the plurality of keywords will achieve a predicted revenue per click level, the keyword traffic dimension data including information indicative of a value related to confirmed registered users, the keyword traffic dimension data including information indicative of a landing page related to a particular cluster of keywords; define a time period of measurement for a metric corresponding to the plurality of levels of dimension data; and store the processed plurality of keywords and dimension data in a keyword database and select at least one keyword from the stored processed plurality of keywords according to the dimension data in the keyword database.
9. An article of manufacture comprising at least one data storage device having one or more computer programs stored thereon and operable on one or more computing systems to: normalize a plurality of keywords received from a source, the source being from the group: a search query and a product listing; filter the normalized plurality of keywords against one or more keyword filtration lists; produce site-specific variants of the filtered plurality of keywords; associate a plurality of levels of dimension data with each of the plurality of keywords, the plurality of levels of dimension data including information indicative of a probability that a keyword of the plurality of keywords belongs to a particular product category in a product category hierarchy, the plurality of levels of dimension data including keyword clustering dimension data, the keyword clustering dimension data including information indicative of a probability that a keyword of the plurality of keywords belongs to a particular keyword cluster of a plurality of pre-defined keyword clusters, the plurality of levels of dimension data including keyword traffic dimension data, the keyword traffic dimension data including information indicative of a probability that a keyword of the plurality of keywords was trafficked by a particular search engine, wherein the probability that a keyword of the plurality of keywords was trafficked by a particular search engine is maintained for each of a plurality of search engines, the keyword traffic dimension data including information indicative of a probability that a keyword of the plurality of keywords will achieve a predicted revenue per click level, the keyword traffic dimension data including information indicative of a value related to confirmed registered users, the keyword traffic dimension data including information indicative of a landing page related to a particular cluster of keywords; define a time period of measurement for a metric corresponding to the plurality of levels of dimension data; and store the processed plurality of keywords and dimension data in a keyword database and select at least one keyword from the stored processed plurality of keywords according to the dimension data in the keyword database. 16. The article of manufacture as claimed in claim 9 being further operable to prune keywords from the keyword database that are not likely to be valuable.