Wireframing applications

Looking for low cost to free wireframing apps. I saw some sometime ago in some design magazines but can’t remember which ones though…

Iplotz
http://www.iplotz.com

Pidoco

HotGloo
http://www.hotgloo.com

Gliffy
http://www.gliffy.com

MockupScreens
http://www.mockupscreens.com

WireframeSketcher
http://wireframesketcher.com

Axure Pro
http://www.axure.com

Just in mind Prototyper
http://www.justinmind.com

Balsamiq
http://www.balsamiq.com