This past weekend, Foursquare held a two-day hackathon in which it invited developers from all over the world to create new apps using the location-based service’s API. Foursquare hosted events in New York, San Francisco, Tokyo and Paris, but developers were allowed to create and submit apps from anywhere.

This event follows on from a hackathon that was held in New York in February, where several interesting apps were created.

Here’s a look at some of the apps that were hacked together over the weekend:

How ______ are you?

Howblankareyou combines your Foursquare check-ins with publicly available census data to show you demographic information from the places you visit.

Flight Graph

This takes a look at your airport-related check-ins to plot your travel history and provide you with a glimpse at where your travel plans have taken you.

AroundMe

This app shows you recommended places along with nearby news, status updates, events and photos. You can also find out what’s happening close to places where you have checked-in.

Sqavenger

Sqavenger is a location-based platform that lets you create scavenger hunts using Foursquare. By following a trail of clues around your city, you can participate in scavenger hunts in your city too.

Placeface

This app automatically switches your profile picture based on the category of the place you have most recently checked into, whether it is a food, shopping, education or travel venue or anything else. Contextual profile photos based on place category? Smart idea, as you can reveal your wild side on the weekend before returning to a more sedate profile photo when you return to classes or the office on Monday.

One More Check-in

Here’s one that will be useful to Foursquare users who love to collect badges. Simply put, this shows you how many more check-ins you will need in order to unlock your next badge. Simple, but effective.

CRawesome

This app lets venue owners see when a social influencer (as indicated by their Klout Score) or a top customer checks-in to their venue. You can also use CRawesome to make it easier for venue owners to reward you by being a loyal customer or a social influencer.

DigiDJ

DigiApp allows you to request a song when you’re in a club without having to make your way through a crowded floor to the DJ booth. It has similar functionality to a jukebox (and perhaps Turntable.fm), in that you can request songs and queue them for others to hear. Pretty cool.

To check out the rest of the apps created at the hackathon and to vote for your favorite, check out the Foursquare hackathon page.