I'm not sure if this is the right place for this but I was thinking about doing a particle system in RGSS via script and a new folder with some particles and possibly using my actor sprites for the emitter, but I wasn't even sure that was possible, and I have found next to nothing on Ruby particle systems, so i thought I would post here.
I have modest experience making particle systems in Flash to simulate spraying blood, fountains, laser beams, space invader type weapons, etc.
I know there are two out there already - Near Fantastica's (http://www.box.net/shared/msrjj1l4qh) and arevulapapo's (http://www.megaupload.com/?d=3ZCFD7E5).
I don't know how well either is made, but I would suggest you take a look at them before trying to make your own.
I like the simplicity of arevulapapos and will probably work with it first. Fantasticas has a lot of options but its got a lot of complexity, like the comment triggered code and compatibility issue of (which version) SDK.