Everyone you know is likely using a location check-in service, but it’s not likely that they’re all using the same one. GeoLorean (99 cents), which works on iPhone, iPod Touch and iPad, can help you keep track of your friends’ locations without having to jump between different apps.

GeoLorean aggregates all the check-ins your friends make to Foursquare, Gowalla and Brightkite, and displays the information in an easily viewed timeline format. Tapping on a check-in takes you to a location map, but no other information, such as addresses or friend information, is included.

One thing GeoLorean does have going for it is its integration of Check.in. Check.in is a mobile app (m.check.in) that pushes your location to multiple check-in services, including Foursquare, Brightkite and Gowalla.

GeoLorean presents its information in a nicely designed, convenient way; however, I can’t say that this app is a must-have, as you’ll still have to manage your accounts through each individual platform. But, if your friends are evenly split among networks, and you simply must know their whereabouts at all times, GeoLorean is worth the download.