iLapse - instant timelapse - is free and does the following:
1) grabs a jpg every 10 seconds into a folder named after the current date inside the iLapse folder.
2) plays back continuously all jpgs inside the folder named after the current date as an endless loop.
you must have a webcam equipped mac.
use "escape" to select your webcam if there are more than one
use "command -q" to quit.