I found Instreamia by chance and let me tell you, it's an amazing tool to learn spanish and 3 other languages, japanese, italian, french and portuguese!
Fun, interactive, complete, very easy to follow, and the amount of information you get in a matter of minutes is unbelievable.
First, the registration process is very simple, then, you get submerged into a virtual world of learning like no other.
You see and hear the words in the desired language while listening to the music or to the voice of a real person reading to you like a teacher; then you can follow your own progress, decide what to do next or return to the prior level.
Instreamia has a very large collection of exercises to ensure the visitor will be learning every minute they spend logged in. When you hover the mouse over a word, you can hear the sound of the pronuntiation, so you learn by looking at the word and listening to it.
To me, as a fully bilingual person, this is, by far, the best program to learn languages I've seen in a long time and I will recommend it to each and every person who needs to learn a new language!