We have just tested the Picframe PhotoCollage app on iPhone 5. This app is free and available in the appstore, as well as on Android. It's a fantastic app and we suggest that you should also use it to make awesome picture collages of your travel photos!
You can choose from tons of collage frames and extra options. Once you have finished, the image can easily be shared with your friends on instagram, facebook, or twitter. For travel photos it is also worth using the text option to add text to pictures of people you meet along the way, the names of sights, and your special travel memories.
An extra note, be clever about how you position your photos in the small frames, focus and angle the image so that the subject of the photo is centered.