prjohnson
With tagging and zero-lag search, it's great for archiving dozens or hundreds of disorganized notes, b/c finding exactly what you need takes 1 or 2 seconds (keyboard shortcut to window and just start typing to search… matching notes instantly appear. Or, for a new note, just keep typing to give it a title and hit enter).
The instant in/out ability (w/ near imperceptible lag) to work with nvALT makes it something I couldn't live without. It's always there, hidden in the background and available. Other windowed note tools require launching the app or opening new windows, often suffering from display refresh lag times or hogging resources (read: OneNote). Opening and using Notes.app (or even TextEdit.app), for example, and flipping between windows and other apps while working is annoyingly slow.
Oh, and might as well give credit to the background syncing with SimpleNote for web / iOS app availability, providing access to notes while on-the-go or at a second machine. Yes, the nvALT / SimpleNote combo is great. Love. Love. Love.