Surfing the web, I stumbled on an iPhone application to make slit-scan images. However, I have no intention of buying a smartphone.
How could one achieve similar results using a dSLR (preferably, but not necessarily, in-camera)?
Depending on what it is you want to photograph, producing a slit-scan image can either be trivial (done wholly in camera), or somewhat difficult (require various contraptions).
Most modern dslr's use a "rolling shutter" which in effect, emulates the slit-scan technique used by cinematographers.
The effect of which is very pronounced when using a dSLR that also shoots video. The so called "jello effect."
So, if you want to try making slit-scan photographs, you can take a photo of something fast (like an airplane propeller), or shake or throw the camera while taking the picture.
Otherwise, you'll need to set your dlsr on long exposure, and setup your own "slit" shutter.
Personally I'd just pony up for an iphone and buy the $1.99 app, rather than toss my camera around or build a shutter system ;)
If you have a video capable camera, I can think of the following way: