I admit: up until a month or two ago I had captcha on my comments. It's the thing where you have to decipher increasingly fuzzy and obscure wording prior to commenting on a blog in order to prove you aren't a robot.
But the more blogs I visited, the more frustrated I became with bizarre captcha screens. Kinda like this:
Half the time I enter it wrong and have to try again, sometimes losing my post in the process. Most blogs - like Blogger - have additional options to block out spam comments. You can choose to log in using google, Wordpress or your facebook or twitter account.
Friendly word of advice: experiment with your comment parameters and consider ridding the universe of captcha. If you insist on using it on your blog, by all means, go ahead. I just can't promise I won't end up like rageface there after commenting.