Most of these have been around for a long time, but they are still effective. And cheap!
#1: Simple Timelapse Rig for a GoPro. You can adapt this hack for any small video cam using a tiny ball head attached to top of the egg timer using hook and loop tape (Velcro), or for more permanent use, glue. It does help to have an egg timer with a flat top.
#2: Arty Filter Hack
#3: The Vaseline Hack. Warning: Be sure to put the Vaseline on a filter (preferably a cheap filer), not your lens. Several photographer have made this mistake.
#4: Flash Diffuser Hack
#5: ND Fillter Hack. If you use several layers of welders glass, you can use shutter speeds so long in a day time scene that fast moving cars disappear from a busy street or highway.
#6: String Hack. For the times you don’t want to carry a tripod. You don’t have the same limitless slow shutter speeds that you do with a tripod, but it will extend your slow shutter speed handheld ability by several stops. Think of this as a cheap, convenient monopod.
#7: Bokeh Hack. Think stars, sliver moons, and other shapes. And you can make more than one cutout, like stars in different sizes.