Markmail

Wow, this is a pretty darn nice email list search tool.  You can easily filter into topics, such as Perl Lists, or Apache Lists and get some very nice analytics along with your search.  Boxes gives trending on your search topic, breakdown of attachments, and which email lists are included.  They seem to have already included some of your average geek favorite toys, such as: (though not all exposed in the interface yet)

• keyboard shortcuts (n,p,j,k)
• sorting (add order:date-forward or order:date-backward to query)
  
• negation (-extension:ppt)
  
• header filters(subject: extension: list: type:)