I used to organize the kids bath toys in one of those mesh  bath toy bags that you get at any baby store.  However the suction cups that hold these bags never stayed on my tub wall.  But I found a better solution; I use the stainless steel corner baskets with the super strong suction cups from Bed Bath and Beyond.  It sticks very well, my kids can easily get the toys as well as put them away and the toys dry fast.  Plus with it being stainless steel, no mildew and it matches the rest of our bath organization set.