Used to do this quite a lot, though my strobe is broken now and I keep meaning to try and fix it. Some observations...
Tryptamines: Looking at strobe with eyes closed, could see swirling colourful patterns onto which were superposed sharp geometric shapes drawn in black lines. The set of colours were often associated with some past memory (e.g. the colour palette of an 8-bit computer I once used, or those that make up the kit of some sports team), though just as often I couldn't place where the colours were from. Meanwhile, the sharpness and thinness of the black lines seemed superior to my normal visual acuity.
LSD: Looking at blank wall or ceiling, the strobe seemed to assist ability to hallucinate superposed images, like colourful parrots or snakes.
DXM: While playing music, some flashes from the strobe were selectively rendered invisible so the remaining flashes fitted the beat of the music. I think other models of strobe can actually do that, but mine wasn't supposed to.