While its a bit funny to watch her try to move towards a toy and progressively get farther and farther away (well, funny until she starts crying about it) its actually a pretty typical step in the learning process. According to the Encyclopedia of Childhood and Adolescence :
Learning to crawl involves a gradual trial-and-error learning process. When infants first get up on their hands and knees, they will make modest attempts at movement, rocking or swaying in the direction they want to go. When they try to move, their balance is unstable and they have trouble coordinating their movements, frequently moving an arm or leg and toppling over. One source of difficulty is the fact that, neurologically, control over the arms and shoulders develops faster than control of the legs. This is also the reason that once the infant is finally able to make real progress, it is often in a backwards direction, because she is able to push harder with her hands and arms than with her feet.Right now Brooke is working on her coordination and I expect she will actually be crawling fowrards in the next couple of weeks.