Here I will be collecting information on Particle and Volumetric rendering, for other advanced type of rendering I have another post to track that, here I will specialize in the volumetric end.
-- Examples --
Realworld example, This looks like what I've been trying to create with particles, someone beat me to it with real glass!
Link: www.flickr.com --- set-72057594061844447
I've done a bunch of work on volumetric/particle rendering.
Link: helios.mine.nu --- Painting with Light
-- Tools --
Link: www.indigorenderer.com
PC only, FREE, similar to Maxwell in It's goals.. It's also slow
Volumetric/SSS
Here It's rendering what appears like volumetric effect using SSS, which is an interesting idea as they are essentially the same thing when your computing it accurately:
Vray and Vray4C4D
Link: www.chaosgroup.com
Link: www.vrayforc4d.com
Vray is brilliant and my rendering engine of choice right now, but It can't yet do accurate dispersion, aberration or volumetrics
I think It's DOF and motion blur are fairly accurate (some things missing for C4D right now), and it can simulate bokeh
Volumetric rendering isn't added yet, but It's coming eventually if these examples are anything to go by:
Link: www.trapcode.com
Fast/realtime particle gizmo for AfterEffects
I knocked up the above image in a few minutes playing with it, very nice, but I have a feeling it will produce images that were obviously done using the plugin, you'll soon have a trapcode form look.
Link: www.sidefx.com
Highly regarded program for all kinds of effects, full fledged software suite for Mac and PC
Link: usa.autodesk.com
Maya fluids, a quick test of mine, It's a 2D slice but it can (if your patient) to full volumetric 3D fluids too:
Link: www.cantarcan.com
Voxel engine for Lightwave, Windows only right now but he says a mac version is coming.
Overburn
Some effects guy who has made a setup for Maya to render particle effects using Maya fluids / voxel dealy
Link: petershipkov.com
Krakatoa : Optimized Particle renderer for 3DS Max
Link: www.franticfilms.com --- work_in_progress_gallery
Lightwave has a built in voxel renderer or some sort called hypervoxels. Though finding any information or examples on it isn't as easy as it should be.