WordPress.com blogs have a great new option for generating tags, and links and thus improving their search engine optimization for posts.
Just go to Users-Personal Settings- and check the options shown. Thats it every time you write a post it suggests links and tags. Links are helpful for your readers (like Wikipedia links to understand dense technical jargon, or associated websites). Tags help to classify your contents so that all visitors to the web site including spiders ,search engines and your readers can search it better.
The bad thing is I need to go back to all 1025 posts on this site and auto generate tags for the archives ! Oh well. Great collaboration between zementa and Automattic for this new feature.
DECISION STATS 
the auto suggest link tag for wp blogs are very nice