Using CLIL to Kill Two Birds With One Stone

CLIL or Content Language Integrated Learning is becoming quite the buzzword in language learning circles. Basically, it's teaching a subject using English to students who don't speak English as their native language. An example of this would be to teach history in English to French speakers in France.
CLIL and Its Effect on EFL
CLIL gets particularly neat if you can further connect the language and subject. You could teach about the American Civil War in English, or perhaps talk about Picasso in Spanish. Many EFL teachers already use CLIL in their classes, they just haven't put a name to it.
My Personal Experience
I've taught art, science, social studies, and history in English. It hasn't been easy. While I studied art at school, teaching science and history was quite challenging. I had to study the material a lot before I could even teach it and if students asked me questions that weren't in that chapter I couldn't always answer them.
Benefits
There are lots of benefits to using CLIL, perhaps the best one is that students get more contact with the target language. Their vocabulary will increase and they'll get more chances to practice using it. CLIL is also motivating since the focus often moves from grammar and vocabulary to content. It also raises the bar for students since they are learning something new in a foreign language and not just the foreign language in a contrived environment. Another added benefit is that students can learn two things at once: a subject and a language. In addition, CLIL can be used with all levels and ages.
Drawbacks
If CLIL is as great as people proclaim it to be, what are the drawbacks? Well, for one, it can fail miserably if not implemented correctly. Since you're teaching two things at once, you could waste twice as much time than if you were just teaching one subject. The other major drawback is that teachers have to be proficient in both a language and the subject they're teaching.
Useful Links

• The BBC's Teaching English has an article as well and activities about CLIL. 
• Cambridge has a couple of guides, such as teaching history and teaching maths and CLIL basics.
• Chiew Pang wrote A CLIL To Climb.
• The European Commission Languages website has info and links.
• Jeremy Harmer wrote a blog post about the pros and cons of using CLIL.
• International House has a course on how to teach CLIL. 
• One Stop English has an entire section with nearly 1000 resources on CLIL as well as a quick intro.
• The UK's National Centre for Language has an introduction and info for English, French, and German.