You either give name/password, or they give you the option to sign in from Twitter. Either way, they will have access to your account which is required to run the app in the first place.
I researched Your Twitter Karma before signing up. Due diligence is essential in all things! I saw nothing but good reports about it.
Thanks Hllary. I'll check out that Twitter Karma. Lately I've been figuring out who's following who by pen and paper. It worked for what I needed up till now, but Twitter Karma sounds like the way to go.
Paul http://twitter.com/bondlife
I have to recommend Dan Hollings' Twitter Toolbar which has a link to Friend or Follow whcih is what i primarily use for pruning followers who don't follow me back and Spammsters/Pornsters.
Mike Cunningham Watch for My New Internet Presence for 2009.