I tell you what I would pay for-
(Either monthly recurring (ala webservice) or as a one off product)
a service/software that hits twitter search for a term ( ie- panda )
and would follow every user who it finds on that term. It does the search every x minutes.
But wait, there's more- If those users dont follow you back after 96 hours, it will unfollow them.
Why unfollow? When you have shit ratios people know you are spam so its important to keep it in normal limits. Also twitter will limit the # of people you can follow if you dont have a certain percentage following you back.
Another cool, but optional feature would be to do a tweet when you follow someone, like "Hey @user Thanks for enjoying pandas- I hope you will subscribe to my panda tweets"
/done
Let me know when someone makes it, Il purchase it.