Anki refers to a free, flashcard-based spaced repetition software available at ankisrs.net. I take just about all of my notes for medical school using Anki. The basic idea is that the spaced repetition allows you to transfer knowledge to long-term memory in the most efficient way possible.
My Anki is broken into three parent decks: Medicine, Languages, and Memory Sports, each with a few subdecks (e.g. Pathology, Chinese). I use hierarchical tags for everything (e.g. Med::Path::Block5::endocrine-pathology::adrenal-cortex::cushing-syndrome). This gives me a way to outline the material. For the cards themselves, I almost exclusively use a modified "Basic" format. Four fields: Front (the question), Back (the answer), Big Picture (additional notes to help strengthen conceptual understanding and see the larger picture), and Mnemonic (usually with a description of images in a memory palace). I don't generally reference palaces or anything other than the actual material in the first three fields. In my Mnemonic field, I'll write something like this: [locus] IMAGE1 hits IMAGE2. For instance, "[railing] EINSTEIN slides into APPLE." Although it doesn't always happen, I do my best to complete all review cards each day, even those from older test blocks.
Here are a few example screenshots: