No. If you wish to use blekko to search, you don’t need an account. If you wish to create your own slashtags, see SEO data, mark websites as spam, or see your Facebook /likes data, then you will need to have an account. You can create an account either directly with blekko by signing up on the join page or you can login using Facebook Connect.
Search blekko help
Tags/date /likes add advanced android API boosting built-in chrome content box crawler create default search delete directory editors firefox homepage ie iPhone link tools mac negation password prefs rss safari safe search scoutjet search bar slashtag directory slashtag of the day sources spam slashtag top bar uninstall widgets wildcards