VocabGrabber analyzes any text you're interested in, generating lists of the most useful vocabulary words and showing you how those words are used in context. Just copy text from a document and paste it into the box, and then click on the "Grab vocabulary!" button. VocabGrabber will automatically create a list of vocabulary from your text, which you can then sort, filter, and save.
Written by a brigh high schooler as a vocabulary quiz system, this free online system looks good. Of course you never really know until you depend on it for some quiz needs. Might be worth the risk!
CoboCards are virtually created flashcards. You can print them and study offline, edit them again and again, compare with older versions, check the status of your knowledge, upload pictures and graphs, include formula with LaTeX, share your flashcards with friends, set a deadline for exams,...