I guess this is as much a question to be sure I haven't missed this, as it is an item for the wishlist for future versions... but non-camera-facing particles that are free to rotate around in 360 degrees would be nifty. I know you can pre-comp a free-rotating piece of footage to then use as camera-facing particles, but for a number of reasons it'd be nice if Particular could do this itself. Just wanted to check and be sure I haven't overlooked anything.
...if this is a valid place to talk about feature requests...
Another aspect of this which would be really nifty would be particle facing/alignment options. For example, the ability to force all particles to face a certain direction regardless of camera. If it worked like rotation and such work now, with a graph (although I'm not sure how it'd work for 3 dimensions) then doing the usual randomization expression to encite a random orientation/alignment/facing would effectively create random-facing particles, with the ability to also align them in certain ways over time, etc. It's kind of a big world to step into, but I think it would definitely be useful.
My particle experience comes chiefly from working at LucasArts, where I used a couple in-game particle engines to do a huge variety of effects... and non-camera-facing particles were very useful, particularly for thinking-outside-of-the-box kinds of effects, and easier/more-memory,time-efficient ways of achieving effects you otherwise would have to use animated 3D layers or elements for. I think that kind of functionality would really help Particular step it up.