What is a good language to learn?

I am bored and throughout the summer I want to improve memory rather then lose it (hah) So what I am looking for, is a language worth learning, I was looking into Hebrew, but I want to know a good book/something that I can buy to help with learning it, or another language I should try, not spanish lol. I didn't like learning spanish, all the programs I tried were to cheesy.. I need something that will teach me for real in any language I decide.. so if you could just list some good languages to try and learn (1 or 2) even if you list two that are easier to learn if you learn the two together.. Thanks