If not already looked at, try Ozmosys (http://www.ozmosys.com) or Esmerk (www.esmerk.com); however be aware that these can be costly and also require initial analysis and understanding of user search requirements (which takes time) and that a % of results my also be considered 'rubbish' by the users - so human intervention always needed.

We have recently developed a Current Awareness system for a top 50 firm which is just going into trial. It was this system which alerted me to this post! Please feel free to contact me if you would like to have a look (phil@uclogic.com).