I put some notebooks for xAct on my website, at http://www.aei.mpg.de/~nutma/. There's an introductory notebook, and two more advanced ones covering the Noether procedure for spin 2 and some calculations for spin 3. Go have a look!
Update (30-04-2016): the above links are dead, but the majority of material in the notebooks have made its way into the xTras documentation as tutorials. The online version can be found here.