My thoughts on the ones I have tried:Crystal Litter (any/all brands):
This would be ok for 1 cat if you can afford it. With 2 cats, the scent was too much (even with regular/daily stirring) and it would have been too expensive. The crystals absorb urine so you are only scooping out solid waste. I tried the Tidy Cats crystals and Dr. Elsey's crystal litter (Precious Cat I think is the name, it's marketed for long-haired cats). Out of those 2, I prefer the Precious Cat. Crystal cat litters are not very heavy. I like the way that crystals look in a litter box if you have an open box (I guess that's kind of a silly reason to use it though).Clumping Clay Litters:
These are nice because they are inexpensive and you can easily scoop out urine clumps and solid waste. The only reason I don't use them is because most are very dusty! I hated pouring litter in to the box. I tried a few brands: Arm & Hammer Super Clumping, PetCo Store Brand, & I think the Safeway store brand. Out of those, the A&H clumped the best by far. I liked the PetCo brand a lot because you can re-fill the jugs and you don't have to keep adding plastic jugs to the landfill. If you want clay, go with unscented. If I went back to clay litter, I would probably use the PetCo stuff.Nature's Miracle Cat Litter:
loved this EXCEPT I had serious tracking issues with it. It has a pleasant scent, it clumps well, and no dust. Also very light.World's Best Cat Litter:
this is what I use. It's like Nature's Miracle sort of and it's made from corn. It has a pleasant scent and no dust. Plus I like that it's light, because it's not such a pain to haul in from the car. Expensive but worth it.
Article about natural cat litters:http://cats.about.com/od/accessories...miumlitter.htm
Article about controversy over clumping clay litter:http://cats.about.com/cs/litterbox/a/clumpingclay.htm