I don't know why I keep forgetting about this wonderful resource, but I thought if I blogged about it, then perhaps I would remember it better. Let's see if it works...
Tecla is a monthly magazine published by the Consejería de Educación which is part of the Spanish Embassy in the United Kingdom. Each month there are three articles at three different levels (beginner, intermediate, advanced). Comprehension exercises accompany each one along with the answers so that you can check yourself.
I could see this as a resource for the classroom teacher, homeschool teacher and adults who are studying Spanish on their own.
Edited: Updated link - 2/27/2012