I studied Spanish for about 5 weeks before arriving in Paraguay, a few hours each day, starting with absolutely no knowledge of the language. While I’m still unable to understand most conversations (mostly due to the speed of speech), I’m making a lot of progress each day. Here are the resources I have been using to learn, most of them for free:

• ProSpanish has a couple of free lessons, which act as a great introduction to the very basics.
• SpanishDict has about 25 video lessons available. These are good, if you can stand the horrible American accent of la profesora!! And there are some interactive activities after each lesson.
• BBC Spanish Steps complements the above nicely, with some good practice for listening.
• LiveMocha is a fascinating website combining language learning with social networking. After completing some interactive learning exercises, you are tested on writing (answering a short essay question) and speaking (recording into the microphone). The magic part is that your work is then handed off to a native Spanish speaker (another community member, who might, for example, be using the site to learn English), who provides feedback and corrections.
• NotesInSpanish is a useful podcast to complement the above, which we listen to in the car.
• I bought the book “Spanish Verb Tenses” by D. Richmond. Very useful, it’s a textbook which includes many exercises that drill the verb conjugations into your head.
• I also had a few private lessons at my house before leaving.