Well, if you don’t have Photoshop — or are just very lazy — then snapmania’s Tourist Remover is option for you. The web application can digitally shoo away undesirable objects like meddling tourists and passing cars. Using it is easier than the Photoshop method because the Tourist Remover does all of the dirty work for you.
You just need to snap three to ten photos of your scene, and you must keep the camera in the same position for each shot. (A tripod helps, but one isn’t necessary.) Try to keep the lighting, aperture, and shutter speed the same for each photograph. Also, you should try to take your pictures so the unwanted objects appear as differently as possible in each image.
Then, just feed those images into the Tourist Remover, and it auto-magically combines the static areas of the image to give you a clearer view of the background. That’s it! I haven’t had a chance to try it out, but the Tourist Remover gallery shows off some pretty good final products.