To use this information, a user selects the Direct Hit option, which will likely appear above the regular search results. This will bring up Direct Hit's own list of what's relevant, where pages are ranked by user popularity. The system is ideally suited to general queries of one or two words, which are common on the major services. A suggestion to try Direct Hit will probably only appear in response to short queries like these, similar to how the RealNames option appears only for queries of three words or less at AltaVista. The Direct Hit option will also only appear if enough data on a term has been gathered.
Some problems immediately come to mind.
Spamming is foremost. The chief defense against this is the sheer amount of data that Direct Hit samples, which makes it hard to skew things. Those attempting to do so are likely to spotted. There are also some other tricks Direct Hit has to help control spamming. Another problem is the fact that many users don't search deep.