Bubbles. Still a big winner in our house!

I always do new toothbrushes, baubble bath, little bath toys, a new sippy or water bottle, crayons, and new coloring books... Just cheap little things that will get everyday use!

Carebears! There are 7'' smaller ones that fit perfectly into a stocking and look so cute poking out of the top.

I made up a bunch of felt stuffed animals, since DD doesn't chew on soft toys. They were actually really easy to make and cost bugger all.
http://farm1.static.flickr.com/203/510517608_2832806a6a.jpg

Teething or chewable toys- something that reaches back far enough to get at the molars, like a teething wand.

Fridge magnets- big enough that they can't swallow. I bought alphabet and number magnets, since we're just beginning to teach DD how to read. I've seen electronic ones that are pretty cool- they were on amazon.

If they still use a pacifier, they make great stocking stuffers.

Movies make great stocking stuffers too. My little girl loves Dora, she's a little older than your girls and has been watching Dora religiously since she could talk and tell me she loves it. Her first word was Dora, hahaha.

Bath toys are great. My little girl loves the ones that squirt because she tries to squirt me with them when she's taking a bath, but always squirts herself on accident and it makes her laugh.

Socks and stockings are great stocking stuffers as well.

Board books are great too. I find that with the children I nanny for, and my own daughter, the Sesame Street book... A Monster At the End of This Book is very popular. Everyone loves it and it's an entertaining reading experience for children and adults alike.

First how cute are your girls!!!!!!!

Bubbles like suzy suggested are great, coloring books and BIG crayons not the small ones.
Things they might need, socks, shampoo.
A letter from santa??if you do that.

Movies, stickers.
I am doing chapstick, girly kind that smells and taste like different desserts...but she is 2.5. i don't think she will eat it :)