Fact Monster's Tigers encyclopedia article, short and sweet!  http://www.factmonster.com/ce6/sci/A0848719.html

Wikipedia's Tigers article, longer and more detailed; a harder read.  http://en.wikipedia.org/wiki/Tiger

Here is Wikipedia's Siberian Tiger article.  http://en.wikipedia.org/wiki/Siberian_Tiger

And this is Wikipedia's Bengal Tiger article.  http://en.wikipedia.org/wiki/Bengal_Tiger

National Geographic for Kids has this great article about Tigers. Be sure to click the arrows to read the entire article.  http://kids.nationalgeographic.com/Animals/CreatureFeature/Tiger

Cool article from National Geographic for Kids about Siberian Tigers.  http://magma.nationalgeographic.com/ngexplorer/0311/articles/mainarticle.html

Discovery Channel's Tiger feature is great.  Check out the "Nearly Extinct" portion of the home page.  http://dsc.discovery.com/convergence/tigers/tigers.html