I just finished a marvelous book. :) It's "Brightly woven" from Alexandra Bracken.
Ms. Bracken has a blog.
Here is the cover of the book.
There are several reasons I like this book, but probably the most pressing is that it's about a girl who thinks she's ordinary, but then finds out she has a lot of power and ability. With that power comes the possibility for her to harm those she loves without meaning to, but also with that power comes the opportunity for her to help her loved ones.