Correct list of post under categories

Hi Dave

This commit is to fix how to list posts under some categories

![oert1](https://f.cloud.github.com/assets/314607/1726983/a9a63bcc-6297-11e3-80fd-a103555b3eb3.png)

The problem is that no post is under "practical" category, but under some name like "letter", "page".
Do we should move these to 1 of 3 known catefories?