In a 2003 article by Online Journalism Review, J.D. Lasica classifies citizen journalism into 6 catagories:

Audience participation at mainstream news outlets- this involves user comments attached to news stories, staff weblogs or newsroom-sanctioned blogs, photo or video footage captured from personal mobile cameras, or local news written by residents of a community.  

Independent news and infomation websites- These run the gamet from individual blogs (Soundbitten), to  consumer news (ThemeParkInsider, Consumer World), political news (Drudge Report), or niche topics (Gizmodo).

Full-fledged participatory news sites- At such sites, citizen-reporters contribute a significant amount of material. Examples of these are OhmyNews and Indymedia.

Collaboritive and contributary media sites- These sites mesh blogs and discsussion boards and allow users to contribute editorial content.  Slashdot,  Kuro5hin and Metafilter are examples of this. 

Other types of thin media- examples of these are mailing lists, email, and newsletters

Personal Broadcasting Sites-  these include video broadcasting sites such as Daytonabeach-live.com and audio sites like KenRadio.com