If your asking where can you open your blog, then the answer is almost every web 2.0 offers they members blog opening. (netlog, tagged, ibibo, livejournal, treemo, ...)

Or if you ask for blog software then you dont need to search for any other than wordpress which is the best blog tool online, and i think that for long time it will stay the best.

P.S. i'm as well interested into websites where i can open blogs, specially UK based websites.

Thanks to very active communities, Wordpress and Blogger have become more like cms that just blogging scripts so in that respect you could probably use a cms like Jommla. If you want something designed as a blog there is a script called phpblog which you can find on Hotscripts, but I doubt it is as good or well supported as Wordpress or Blogger.

There are many other blogging platforms but amongst them wordpress and blogger are the best i think. Joomla is the another one which offers good tools and is a great CMS as well. If you want more freedom you can choose a web hosting plan which will offer you great support and tools which will help you to increase your website ranking in major search engines. Using the feature fantastico, you can your own blogs in just few clicks.

you can now blog on vbulletin also, thought it has to be enabled by the admin of the forum, you have lots even social network sites such as ning are hosting blogs

joomla, drupal are some of the top caliber blogging platforms.
for free bloging and hosting squidoo and hubpages are on top.

Wetpaint is as well good. But im not sure if they have dofollow links? Anyone know?

Hi, not sure exactly what you're looking for when you say blogging platforms, but here is list of web 2.0 sites that allow you to create blogs:

Vox.com
livejournal.com
wetpaint.com
weebly.com
blogsome.com
xanga.com
gather.com
tumblr.com
blog.com

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The blog plat forms are:

1.Google blogger
2.word press
3.six apart type pad
4.square space
5.Lycos tripod

I've only heard of/used wordpress, blogengine and movable, although wordpress is of course the best by far, in terms of plugins, features and general blogging.