I've been on this site all morning. It's great. It's a way to learn new languages. And if you don't care about that, you can expand your vocabulary with the SAT part. I started using it for Mandarin since I'm going back to China soon for college in Hong Kong. I won't need another language since HK is mostly English, but I think it would be quite helpful for me to at least learn the language.
They give you a batch of words you slowly study and get tested on. You're helping your garden(Brain) grow by how well your memory is. You start with a seed(No knowledge of the word) and then begin the test into a small plant for your short term memory. Once you are prepared enough, a clock will start a countdown for 20 hours. When the 20 hours pass, it will say you are ready to test your long term memory. As soon as you pass that, you finished planting your first seed that blossoms into a full plant to go in your garden, thus completely your little steps towards another language.
I haven't started the long term yet as I had just found this site, but this has been immensely helpful.