It had to happen, someone felt that RSS feeds were just not enough. TweetStalk created a Firefox add-on script that allows you to select Stalk and/or Follow when viewing a profile on the Twitter pages. From their homepage:
Sometimes you want to follow someone on Twitter, but you don’t want them to know you’re following them. We present to you TweetStalk ‒ the simple way to stalk Twitter users without having to follow them.
I am not sure how many of you have interest in this, but the offering is there, only in Firefox. Sounds like something that should be mentioned on SocialStalking.com
They have also introduced their own webpages that allow you to create groups and watch them from their web interface.