Thank someone for following you on Twitter!
Create a filter in Gmail so when you get an e-mail about a new follower on twitter, you automatically send a tweet thanking (and tagging) the new follower. Your Gmail filter will be a search for "is now following you on Twitter!" in the subject line. This filter is to apply the Label 'TwitterFollow'. Then IFTTT tweets "Thank you for the Follow! (Person Name (@twitterhandle) is now following you on Twitter!)". It's dirty and not very customizable/personalized, but it gets the job done.
Applet ID 61183p