Vocabee is a learning tool built on the Leitner system, the method of repeating new imput in 5 cycles at increasing intervals. Designed for learners of any subject and language, it lets you repeat the content you enter in one of two modes:
Using the "gezielt lernen" mode, study a selected unit to prepare for an exam, storing the content in your short-term memory.
Choose "langfristig lernen" to study using the 5 cycle method, to store the content in your long-term memory.
This tool, launched in January 2011 and currently in beta, was developed by SeitWerk. The makers promise that vocabee will remain free, and they guarantee that what you store there will still be available in 10 or more years. They also promise that they have a lot of ideas up their sleeves to improve on the app.
There is currently a lot of nice free content already available for English and Business English. It was collected by an advanced learner of English (whom I know), who got most of his input from studying at Language World in Starnberg.