New Alternatives
1.Simploo
http://www.simploo.co.uk/product/simploo-waterless-composting-toilet-compost-toilets-eco-loo/
Looks nice like a hatbox toilet, but still a bit too much depth.
2. Kildwick.com
Same as offgriddesigns mentioned earlier. They have made several innovations, including (a) anti-microbacterial built-into separator, (b) turning mechanism for solid wastes (optional to compete with Airhead/Nature Head or no mechanism like Separett for easier disposal), (c) exhaust fan built into exhaust tubes, and (d) new, much smaller.but same solid capacity Koodle.
The Koodle is waterproof for wet baths, portable for relocation, small non-permanent exhaust hose, etc.
I like the nice smooth surface and the toilet lid which is flush with perimeter.
I can't tell how it is permanently or semi permanently affixed (floorplate or bolts?), whether the solid waste container can only be removed from side or from top, etc.
The Koodle has great possibilities. I think its small size and better aesthetics than the other Kildwick models make it a model to track.
https://www.facebook.com/koodleloo/