Baluns can be very useful for the radio amateur. Also, there is much mis-understanding on what baluns can and cannot do. In addition, the wrong balun application can waste your transmit power and receive effectiveness. Further, it can cause unnecessary QRM, TVI, and in the extreme case, fire.
The links below direct you to articles pertaining to baluns. They are in no particular order of application or importance. We recommend you skim through all the articles at your convenience and later study carefully those of interest.
Balun Information and Operation
Common Mode Chokes W1HIS April 2006
Baluns – How They Work Roy Lewallen, W7EL (basics of RF currents in feed lines and coax)
Some Aspects of the BALUN (adapted from QST, March 1983)
RFI Ham Balun, K9YC Jim Brown, K9YC, April, 2008 (61 pages)
Dual Core Balun Construction Project
W1GC Low Power Balun
Current Balun using Ferrite Rods, ZS1JHG
Putting a Balun and Tuner Together, W9CF
Balun Operation G8JNJ (practical info – heat signatures of balun under stress )
Vendors and Balun Supplies
RadioWorks (nice list of balun products and balun theory. You have to browse the site to find the balun info)