I think that Flocabulary is an excellent resource.  It presents vocabulary and more compex ideas in a school friendly rap. You can use it as a hook or as a mid-lesson wake them up (especially in a 90 minute class).  It has excellent ancillaries.  I've also used it for tutorials after school and on Saturdays. It has a free trial period, but the monthly cost is reasonable. 

The kids go away humming. Here's the website: www.flocabulary.com