There are many categorizations of blogs by different purpose and different target of audience. Here are some examples of the classification types in subject matter of:
Politics: Dr. Mahathir Mohamad (previous Prime Minister)

(themalaysianlife.blogspot.com)
Fashion: Carven Ong (Malaysia Fashion Designer)

(elyzabetheng.com)
Device: Moblog – moblog is mobile blog. The blogger is using the PDA or hand phone to maintain the updating of a blog. (Tech Target 2008)

(darrenmillar.net)
Media type: (examples)
a) Vlog. A Vlog is blog that consist of video.
Vlog is becoming very general when this tool becomes cheaper and sustaining software and hosting becomes more established. (Tech Target 2008)

(tamatheweb.com)
b) Sketchlog. Sketchlog is blog that using sketches (EzineArticles.com 2009)

(lubasa-sketchlog.blogspot.com)
c) Tumblelog. Tumblelog is a blog that with sequence of links, video, images, quotes and short blurbs. (Pixelspread 2008)

(livetardy.com)
Status of publishers:
a) Business blog

b) Corporate blog

(bernaisesource.blog.com)
In my opinion, I think that Vlog is mostly useful for the readers because the vlog provides video so that people can understand more and know more about the things that they want to know. According to Henrickson 2008, vlogging can help to attach the bloggers with the readers on a further stage. Besides that, instead of writing 3 articles, we can just combine them into a video. The transition of the vlog is much easier and it can make different topics into a better flow. ( Henrickson 2008)
Blogging Communities
According to White 2006, online community is to share some “initial thinking”. Currently, the power of blogs has introduced a new platform for communities. The blogging community is the group of the bloggers or readers that link together. They share opinions and leave comment and talk about the topic that they are interested. Wei (n.d.) notes that blogs are always within a blog community of similar interests. The communities are useful because each blog community has their own practices for people to use as guidelines.
Example:
blogcatalog
(azikuri.com)
References:
EzineArticles.com 2009, So you want to blawg do you, viewed 12 June 2009,
http://ezinearticles.com/?So-You-Want-to-Blawg-Do-You?&id=2230121Henrickson, M 2008, Is vlogging the best way to blog, viewed 12 June 2009, <
http://blogaboutyourblog.com/2008/05/01/is-vlogging-the-best-way-to-blog/>
Pixelspread 2008, What is a tumblelog, viewed 12 June 2009,
http://pixelspread.com/blog/223/what-is-a-tumblelogTech Target 2008, Whatis.com:moblog, viewed 12 June 2009,
http://whatis.techtarget.com/definition/0,,sid9_gci1180174,00.htmlTech Target 2008, Whatis.com:vlog, viewed 12 June 2009,
http://whatis.techtarget.com/definition/0,,sid9_gci1163516,00.htmlWei (n.d.), Formation of norms in a blog community, viewed 12 June 2009,
http://blog.lib.umn.edu/blogosphere/formation_of_norms.htmlWhite N 2006, Blogs and community: launching a new paradigm for online community, viewed 12 June 2009, http://kt.flexiblelearning.net.au/tkt2006/edition-11-editorial/blogs-and-community-%E2%80%93-launching-a-new-paradigm-for-online-community