There is one called Xapian. I haven't used it but I've heard good things.
I've used Ferret ( Ruby ) and worked for me, unfortunately it only works in ruby 1.8. X , (It's not supported in Ruby 1.9) Other solutions were already mentioned: Sphinx, Xapian , also SolR ( based on Java/Lucene) should work).
An old yet good reference. wrg.upf.edu/WRG/dctos/Middleton-Baeza.pdf.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.