What are the best ways to study a foreign language without taking offline traditional courses?

http://Babbel.com is amazing.  My husband and I have been using it to practice German and it has by far the best cost-to-benefit ratio of the other programs we've used. (We've both tried Rosetta Stone, Pimsleurs, and other language software with little success).  It has various ways of practicing the language such as fill-in-the-blank with writing and speaking, multiple-choice, choose-the-picture, etc. Another great resource are various apps offered through Android.  I don't have an iPhone (gasp!) so I don't know what is available through the Apple marketplace, but Android offers some good free apps that help you practice various languages.  Look for flashcard programs and language programs. I've seen specifically Spanish, German, and Italian, but I'm sure there is more in other languages as well. I have also found various culture centers (eg: a German Deli) helpful as they sell magazines in the language.  Reading these and having pictures helps just as teaching a young child with pictures would. They may not always be able to read all of the words, but knowing most/some and having picture clues to go off of really strengthens their understanding of the text and language. Lastly, I've found that watching videos and looking at websites in the language you want is very beneficial to maintaining what I have learned.  I may not get ALL of it, but for the pieces I do get, it helps me understand the language and keep up the practice of using it and thinking about it.  Try searching in Google" "Google in _____" whatever language you want, it will give you google in that language and also search sites that are in that language.

Writing a daily journal in your target language is a good way to retain/practice it, just to force yourself to make use of it. You could even try something like http://lang-8.com which is a site that will host your journal and allows others to suggest corrections; hopefully you can help correct their journal entries as well.