Study Spanish is a good resource for locating Spanish language instruction and practice quizzes. Not all of Study Spanish is free, but there is enough free material to warrant mentioning it on Free Technology for Teachers.

Study Spanish offers students free accounts in which they can read tutorial materials and then test their new knowledge on free quizzes. Students can keep track of the items they did and did not know. Teachers can create free accounts to monitor the progress of their students.

Applications for Education
Study Spanish is not going to replace teachers in the classroom, but it is a good supplementary resource for Spanish learners.

Here are some related resources that may be of interest to you:
Euronews – News in Eight Languages
Large Selection of Language Learning Games
Teaching Spanish – Resources and Lesson Plans