CherryTree - A hierarchical note taking application, featuring rich text and syntax highlighting, storing data in a single xml or sqlite file.
Typora - A minimal Markdown reading & writing app.
Cryptee - Cryptee is a safety and privacy focused, encrypted and cross-platform personal data storage service. You can write personal documents, notes, journals, store photos and all sorts of other files.
Markdown by DaringFireball - Text-to-HTML conversion tool/syntax for web writers, by John Gruber
Lastpass - LastPass is an online password manager and form filler that makes web browsing easier and more secure.
Minimalist Markdown Editor - This is the simplest and slickest Markdown editor.