Ninja follower taps out at 100 users, is web based, requires you to gather up all the usernames you want to follow, etc etc, ad nauseum.
If you know who my company is (some of you long timers here do) then you know we don't like to screw around with time wasting nonesense like that.
Hummingbird is fully automated, fully compliant with the Twitter TOS, and automatically ensures you are following the undocumented Twitter follower/following anti spammer ratio.
We've done extensive development with the Twitter API and even have services featured on the site (like our @whoot twitter follower predictor).
Great input guys, keep it coming.
BTW, even if Twitter is not your bag, it has managed to attract well over 6M users and growing. The market is primed. The limitation is a marketing mechanism. Nobody here is fresh off the boat, we know how this game is played.
Sign up as an affiliate, pocket the profits.