I got this idea after trying to link many keywords in my blog posts. All the time I needed to click on the link tag to link that word to a specific site. When users browse any blog and they found certain thing interesting they will love it if they can just click on it to go to the concerned site to find more info.
For example if a post contains the words "google" "gmail" "yahoo" "yahoo mail" etc.. they should be linkified with corresponding urls http://www.google.com, http://gmail.google.com, http://www.yahoo.com, http://mail.yahoo.com like that..
I think a plugin which will enable bloggers to link some common keywords with urls in their posts will be good. What say u?