Here are two links to websites run by people I admire for the work they put into creating their websites. Kirt has tirelessly found a way to make a living at his and Pete has put great effort to create his to pass along his knowledge on fourier theory.
RF Cafe - An extensive resource for RF, wireless, and all aspects of science and engineering. I have been watching Kirt's website for a few years and I think it is a great resource for people interested in RF engineering:
thefouriertransform.com - A great resource for the fourier transform. This site was put together by Pete Bevel. Lots of good material to digest. He has a deeper understanding of this stuff than me :-). He also has links on this site to other technical websites he put together about antennas.