Wikis are collaboritive websites that can be edited by multiple people. Many Wikis require an account to edit the content on different subjects. An example is Wikipedeia.
Podcasts are many type of media that can be published and downloaded. As many people know, Itunes has an entire podcasts option where you can download podcasts from different publishers.
In my opinion I prefer Podcasts because it promotes more creativity. Although they are not necessarily “collaborative”, I seem to favor them more than podcasts.
Wiki Example: http://capebit.wikispaces.com/
Podcast Example: http://www.podcast.com/
Characteristics of podcasts an Wikis:
Wikis use specialized wiki software
Wikis enable users to create pages collaboritively
Wikis are widely often considered “Unreliable” because of the unkown authors
Wikipedia.com is the largest Wiki. It contains thousands of wikis on different subjects
Podcasts are any types of media that are published
Podcasts can be a speech, video, or PDF
One of the biggest podcasting downloading sites is directly from Itunes