Baba Yaga, like many wicked witches, is known for kidnapping children and threatening to eat them. She's quite a bony old lady so I can only surmise that she doesn't get to eat many of them. She's not the most conventional which however and travels in a giant pestle, using the mortar to steer. Her broomstick is reserved for removing traces of where she's been but the pestle and mortar combo does enable her to fly. She lives in a little wooden hut which stands on chicken legs.
She is a common character in Russian and Eastern European mythology. These stories are very similar to those of the brothers Grimm, full of innocent maidens, mean stepmothers and unwanted children. The story of Vasilisa is one of the best known and it has several familiar elements to it. The full story can be read here. Although she is a fearsome character, if treated with respect she will do the same and the villain of the stories is usually not her.
She does crop up now and then in modern fantasy fiction. I recognised the name in one of Patricia Briggs' Mercy Thompson books, where Baba Yaga is fae. I know I've seen it elsewhere too but she never gets a starring role.
Some books featuring Baba Yaga that you might find interesting (links go through to amazon.co.uk):
Have you read any books featuring Baba Yaga that you'd like to add?