Pimsleur Spanish CD set
I used the CD set for Pimsleur Spanish. I found the learning style to be the best for learning without memorizing random words. You learn strictly through conversation with the system.
My finance's family was from Ecuador and I wanted the easiest way for me to pick it up and they were quite impressed at how quickly I grasped the language. I tried several other methods (including Rosetta Stone) and found it much easier to learn with Pimsleur. Thirty minutes a day was easy to do.
It's also nice the way they break the lesson up. The first half is review of the previous lesson and the second half is new material. Also, all the conversation is in the formal tone. I found this to be much better than the informal tone of some of the other similar products. The tone is very important to the people that speak Spanish and I'd rather speak with a formal tone than an informal and insult someone.
At the time, I was using the lessons solo and I wasn't using any additional products. I was doing a fair amount of commuting, so using them in the car was fantastic. I enjoyed the fact that I didn't need to sit and read and try to write. I could just drive and speak. I highly recommended Pimsleur.