Here’s a neat trick I found that allows you to follow in one action all the twitter users that are presented in a single page on twitter, you can use it on the search results or you can do it on the Followers or Following page of a given user.

Twitter is using the jQuery JavaScript framework so you can call the click() function on all the Follow buttons for all of the users on that page, at the moment of writing this post every twitter Follow button. Open the Twitter page you want to perform the mass follow, scroll down as much as you want to increase the number of users Twitter is displaying.
Now open your browser’s JavaScript console (usually CTRL+Shift+K or CTRL+Shift+J) and input the following jQuery code:

a = setInterval(function () {
window.scrollTo(0,document.body.scrollHeight);
Array.map(document.getElementsByTagName("div"), function(x) { if(x.textContent === "Follow" && x.getAttribute("role") === "button") { return x.click() }})
}, 6000);

We’re selecting a span inside the button object, if it’s of class .follow-text and it’s visible, we want it’s parent – The follow button and we perform click() on that button.