On my blog, I require users to register with Wordpress before commenting, mainly to prevent SPAM. Does this deter you from commenting on blogs? I'm considering removing the requirement, if it would help boost comment numbers.
Just let them comment and filter comments. I would set it up so you have to approve each one before it shows up.
i never register to make a comment - i just move along.. Just get the Akismet plugin and you wont have to worry about spam comments ever again.
u can just as well close the comments section fully, no one will bother to register just to leave a short note like "thanks for the info". If u want to filter annoying spam, just add askimet or image verification.
If you want your readers to comment, don't make them register - they won't. Install Spam Karma 2, Akismet or Math Anti-spam protection and watch your comments from time to time. I suggest you don't approve each one manually because users prefer when their comments show up immediately.
I know a lot of people do not like Akismet but I have found it work pretty good. You will need to sign up for a WordPress account to get the API key though.
Of course no one will bother registering. Use bcSpamBlock and Simple Trackback Validation. This combination is far better than the famous Akismet.