Does your camera have a time-lapse mode?
Can your camera record a video? You can process the video later [with, e.g., Virtualdub] to change the playback rate or else selectively keep frames.
You can try to build a remote shutter. Although the following describes a Canon camera, something similar may work for other cameras.
(I built my own for a Casio camera... by interfacing to a USB cable. The next step would be to somehow connect it to a PC and control it with software.)