1. Read: you may find something that suits you here or here. If you are looking for teen or young adult literature, click here and here
2. Listen to English; podcasts are a good idea: try here and here. Songs are also great to practise both listening and pronunciation; have a look here. By the way, besides making you feel good, singing songs is encouraging as for English learning: have you noticed people have accents when they speak English but not when they sing? Isn´t it weird?
Here´s a video that shows what a podcast is and how it works:
3. Play some games online. Try this one: Placefy - fun geography game, twitter game, travel game. Besides, there are different types of games in my Delicious links as well.
4. If you are willing and able, you can take a special summer course; you can choose any of these: an elephant camp in Thailand, learning ice-cream making in Italy, learning Senegalese drumming and dance traditions in Senegal... for these and many more, click here
5. Watch films or documentaries in English. You will find some very interesting ones in this link, SnagFilms