I read a clever joke on Twitter the other day: The Internet is now a giant app for Facebook.

With Facebook poised to take over the world’s communication, and with Twitter following behind, it's the question is on the tip of every iPhone addict’s tongue: Will the other location-based apps survive when Facebook finally rolls out their location strategy?

While Facebook will likely become more integrated with the iPhone, here are some established iPhone apps that already have a strong following and are likely to survive if Facebook takes them on directly. I’ve thrown in a couple newish ones that I think might have a chance of surviving Facebook world dominance, too; the best part is they are all free.

FourSquare

I’m addicted to FourSquare, and I’ve directly benefited from compulsively checking in everywhere I go. I recently became the mayor of my neighborhood salon and spa on the free FourSquare app, and the spa appropriately awarded me with a free massage because of it. Basically, you check in at restaurants, stores, gyms, etc. and for every check in, you receive points. Gain more points than all the other users, and just maybe, you will be awarded the coveted mayorship of that location. You can share your check-ins on Facebook and Twitter, too, and earn special badges for exploring distinctive locales. FourSquare currently dominates the location-based app market for iPhone; more and more of my friends join every day.

I was somewhat dismayed at FourSquare’s decision to only award points for check-ins that happen within a certain distance of the location you are checking in it. I understand there are cheaters out there, but I enjoyed checking in after arriving safely home and avoiding any would-be stalkers. Plus, I use a, iTouch and not every place has Wi-Fi.

Yelp

While the Yelp website announced integration recently with Facebook, which among many other things allows users to “like” companies on Yelp and instantly “like” them on Facebook as well, the free Yelp iPhone app itself is pretty stellar by itself at finding a recommended dining spot. Yelp has a cult-like following, including those with elite status that deliver real-people reviews of restaurants and businesses all over the country. Simply log in to the app and by using your current location and get plugged into the hottest joints all around you.

Gowalla

The free Gowalla iPhone app distinguishes itself from the similar FourSquare app with pre-created trips that users can experience in order to collect special badges for their Gowalla passport. Users can also check in during routine daily stops as well. I’m not an avid user of this app, but I am curious to check out the plethora of nearby trips to earn some badge cred with my Gowalla friends.

Whrrl 3

Whrrl 3 promises to save you from Farmville hell when you use their app for real social interactions. The free Whrrl 3 app encourages users to do more than just check-in, users are encouraged to visit locales in order to join societies such as “Chicago Brewpub,” “Supersized,” “Pie in the Sky” and “Furry Friends.” This iPhone app also has a section to notify you of special deals, something my beloved FourSquare lacks. Between Gowalla, FourSquare and Whrrl 3, Whrrl 3 wins the best designed interface, hands down.

Skimble

This is the location-based app for athletes to keep track of their activity. The free Skimble iPhone app let’s you compete with other athletic friends to earn the most workouts of the week. Record all the details of your workouts and where you are working out at.