Most notable on the list is Audacity, which is a F/OSS (Free and Open Source Software) sound editor licensed under the GNU GPL. I've recorded over 60 podcasts with Audacity and it's done a great job every time.
Another mainstay on the list is the Creative Commons. While the CC isn't an application, it is a process or program that empowers the grassroots community to share their works with some legal propriety.
And last, but not least, is the OGG format. WIthout dragging everyone down into the weeds with me, let's just call OGG a royalty and patent free alternative to the MP3 format.
I'm tickled pink to see such a heavy showing of applications and tools that can be used for podcasting in a top 10 list.