Conventional artistic wisdom skews heavily against drawing from photography. Indeed, the oldest example I’ve found is from Solomon Solomon, arguing against it when cameras were still industrial monstrosities, rather than something we all have in our pocket.
I contend that part of the reason photo drawing sucks is that you have infinite leisure to use the photo. Thus, you dawdle and over-analyze, and it ends up stinky. A live model’s continually subtle shifts make the artist’s brain process the real essence of the pose, even if it’s an hours- long pose. Therefore, if your photo reference is held to a 30 second to 10 minute window, might you be forced to process it faster?
Other unorthodox sites let you fake it, with enjoyably more random results. At times my homepage has included Arkive.org’s random species, Flicker’s Interesting Photos from 7 Days, or Panoptikos, which jams a bunch of photo subreddits together. This lets you hit refresh until you see something you like, then draw it. But you get the two downsides: Choosing your subject (resulting in refreshing for 15 minutes) and no time constraints.
However, the best lifedrawing software out there is right behind this window! Right now! It’s your desktop.
First, spend some time on the internet hoarding pictures of interest. I tend to seek out pics with good costumes, interesting characters, nudes (get this: they’re all over the internet!), faces, and animals, but I try not to be picky. Save ‘em all in a giant folder. Mine’s got over 14,000 pics!
Next, change your desktop background preferences to use that directory, and change randomly every 30 seconds, 1 minute, 5 minutes, etc. Set your computer down, and just draw whatever shows up as your new wallpaper.