I go into much more detail about this in my blog, where I boil down the concept of making more friends to as close to science as it gets.
People make more friends at the rate and speed that they are introduced to new people.
There are two ways to meet new people.
1. Introduce yourself to new people
This is what 99% of people tell you to do when you ask them how to make more friends. This works, except that you only have so much time and energy.
2. Get introduced to more people by your friends.
This is where the true power of becoming massively popular lies. Of course, this depends on whether you have friends who know a lot of people.
Making friends with the "right" people can literally land you with like a couple hundred friends over night. I call those people "social connectors". Social connectors are people who are very well connected with other people. They aren't typically hard to make friends with - that's why they have so many friends. Example: If you're looking to meet more girls, a good social connector to make friends with might be the flamboyant gay guy who's bbf's with a million hot girls.
Making friends with social connectors seems obvious, yet no one does it. Notice how many of your own friends are social connectors...
Once you've done this, you will become very well known. If you make friends with 5 ordinary people, you have 5 new friends, and they will introduce you to their 5 friends. That's 25 people.
If you make friends with 5 social connectors, they will introduce you to their 50 friends. That's 250 people. Seriously that's no joke.
Once you've done this, you can organize some group activites some of the other posters suggest. Presto, you have all the friends you can handle.
I go into severe detail on the science behind how to make more friends in college and climb to the top of your social circle on my blog.
Find more info here: www.TheCollegeCupids.com