1:1 Current Balun by N5ESE
Here's another handy little Altoids QRP project. For Field Day 2002, I wanted to use my new Elecraft K1 (which has an automatic antenna tuner built-in) to feed a full-wave loop on 40 meters, to use on all bands 40 - 15. To preserve the feedline balance (I used 300-ohm ladder line), I needed a balun at the output of the K1's antenna tuner. This 1:1 balun did the trick quite nicely.
http://www.io.com/~n5fc/balun_1-1.htm

1:4 Current Balun by N5ESE
Here's yet another handy little Altoids QRP project. This makes a great travel companion to the 1:1 current balun (described -here-), and is intended to aid in tuning a balanced antenna or feedline that has a high impedance (100-600 ohms).
http://www.io.com/~n5fc/balun_1-4.htm

1:9 Balun door PA3GER
Enige foto's van zelfbouw balun 1:9 t.b.v. een longwire-antenne. De 3e foto is een opengemaakte, gekocht exemplaar ! In de 4e foto is te zien hoe Jack PE2JWC een balun in de voet van een 5,5 meter lange verticale 27 MC antenne gebouwd heeft.
http://www.pa3ger.nl/content/view/15/27/

Homemade HF Antenna Balun by AA5TB
A balun is a device that is used at the feedpoint of a balanced antenna when an unbalanced feedline is desired to feed the antenna. Balun is a contraction for BALanced to UNbalanced.
http://www.aa5tb.com/balun.html

QRP Balun by AA5TB
I had a high permeability ferrite rod and an old B&W dipole center insulator in my junk box so I decided to construct a choke type balun for QRP use.
http://www.aa5tb.com/qrp_balun.html