Run, don't walk to Maris Hawkins' blog post Made It Monday: Summer Proficiency Pack. It's for middle schoolers, but please, go look anyway even if you're not teaching at that level or just learning on your own at home.
She has put together a wonderful packet for her students so that their language skills do not dwindle over the summer. She based it on the most recent #langchat on Twitter: Keep Students Motivated with 9 Summer Language Learning Activities. You'll find links to recipe sites, YouTube videos, news video sites, and more.
In her post, she also mentions that Zachary Jones has put together an ebook, Summer Spanish 2013. It costs $5.00 and I imagine it's worth every penny.