You can take a look at Tonegod’s “force-base” ParticleEmitter, it even come with an Editor .
I also have some snippets for advance “force-base” ParticleSystem and can be exchanged with standard JME ParticleEmitter and also can be import from some Emitter editor program.
But first I think I want to know what features you want for your effects. Because more parameters don’t make it look better if you don’t understand how it will composed or don’t have a tool to make it!