Turns out there is at least one - and they sell it at your local drug store (CVS/Rite-Aid/Walgreens/etc.)
It's those chintzy little keychain cameras that they sell for $10-15 a pop. The photography on them isn't half bad with a resolution of about 300 by 200, they can store between 20 and 240 photos (depending on the one you find), and it turns out the little guys were just made to be hacked. You can also do this same hack with a cheap 1 or 2 megapixel camera that takes SD cards if needed (see below), but we'll be stepping through the process used on the more commonly found 300 by 200 cameras.
This Instructable will walk you through the process of disassembling, modifying and reassembling an off-the-shelf keychain camera. It will then walk you through wiring a simple set of transistor switch circuits that can be used by Arduino to turn the camera off and on and snap photos whenever your program desires. It'll also have sample code and plenty of pretty pictures.
Before we start, a few notes:
*The camera being hacked may change from blue to silver and back in the photos. Don't fret, the internals of both cameras are the same (I'm working with both at the moment for research.). This same camera is sold across the country in different colors, under different brand names and even with slightly different physical casings.
*If this technique sounds familiar, it might be because what we're doing to the camera itself is very similar to the technique used by the CatCam, a project that went viral two years ago by putting small, time-lapse cameras on the collars of outdoor cats and watching where they go. The CatCam's technique uses a camera that's not easily available in the United States, and was written before Arduino really took off - hopefully this revisiting of the technique will help the DIY community rediscover and repurpose it in their projects. I discovered the CatCam as this project wrapped up, and both techniques were developed independently - so my technique likely varies from the CatCam technique; feel free to pick and choose techniques from the two.
*If you are outside the US or willing to order directly from CatCam, the hackable camera they sell is of a higher quality - 1 or 2 Megapixel - and can save photos directly to an SD card. Very nice for many projects (but not necessary for all.) But if you want a camera today, head to any Rite-Aid, CVS, etc and pick up the camera shown here - a Digital Concepts camera, usually distributed by Sakar international.
*My research actually has me controlling this camera via a stand-alone ATMega chip. If you're interested in learning that technique for some reason, let me know - if there's enough interest I'll whip up another Instructable. (I figured there'd be more demand for doing it via Arduino.)
UPDATE: By request I've added the circuit diagram to wire the stand-alone ATMega chip to the chip as the last photograph below. It won't be helpful for many of you, and I apologize for that - I hope to give this step its due diligence - but for those who are determined, it's better than nothing (I hope).
*This technique is being documented as part of my research at Carnegie Mellon University's Master of Tangible Interaction Design program, in Pittsburgh, PA. If you are considering going back to school, enjoy making things and are interested in the intersection of technology and design or art, drop us a line! :)
Hope you found this helpful - comments on both technology and application are welcome! Feel free to write me directly or comment if you have any questions or want any clarifications.
Step 1: Assemble Supplies and Tools
*A tiny Philips-head screw driver. (About the size of one you might use to repair glasses, or in a computer repair kit.)
*Helpful, but not critical if you have long fingernails - a tiny flat-head screw driver to use as a plier.
*Wire cutter/wire strippers
*Helpful, but not critical - multimeter.
*Soldering iron and solder. (Now, now, don't fret. All you'll have to do is heat up some existing solder and stick a few stripped wire ends into the existing connections. Only rudimentary knowledge of soldering necessary. You might even be able to get away with wire glue on some models, but soldering is safer.)
*An off-the-shelf Keychain Digital Camera. Often sold under the brand names "Digital Concepts" or "Shift." Sold at CVS, Rite-Aid, Walgreens, some Walmarts, and all over the Internet.
*Helpful but not critical - a few spare AAA batteries. The camera should come with one AAA battery. But if you intend to use your project more than a few times or over long periods of time, you'll need spares - the camera eats them.
*A few feet of insulated wire. (Either normal-gauge plastic insulated, shown, or thin-gauge paint insulated is fine - both have their pros and cons; I tend to use paint insulated because I sometimes make custom male headers for my connections.)
*Breadboard or other protoboard.
*Two longish pieces of white wire (for connecting transistors to Arduino)
*Two longish pieces of black wire (for connecting ground from Arduino to breadboard)
*Two longish pieces of red wire (for connecting high power from Arduino to breadboard)
*Helpful, but not critical - an LED (for debugging output).
*Two transistors (I use NPN 2N3904 transistors.)
*An Arduino with USB cable.