Um, enjoy? The official IRS website is about as much fun as doing your taxes.  But this is the place to go for the official word on all tax questions… if you can figure out what it means, of course. 

The Tax Foundation is a nonpartisan D.C. think tank dedicated to educating the public on the workings of the federal tax system.  Tons of useful reports can be found here. 

Another good source for reports on the federal tax system.  The CBPP offers a more liberal perspective than the somewhat more conservative Tax Foundation. 

Americans for Tax Reform is a conservative group dedicated to lowering taxes.  If you're interested in exploring anti-tax political arguments, this is a great place to start.