Notational Velocity is an application that stores and retrieves notes. It is described as a modeless, mouse-less Mac OS X note-taking application.
I’ve tried many notes application starting from Mac OSX’s own Sticky, to the once-paid-but-now-free xPad to the heavy-weight Evernote and few others in between which didn’t really caught on to me. xPad came very close to be being my ultimate note-taking app and I even paid for it. Evernote is an awesome application but I’ll categorized it as a heavy-duty utility rather than just a note-taking app. Its being mentioned here as it can and do take notes. However, its an overkill for just ‘note-taking’. I use Evernote more to collect/archive documents, adding notes on top of them and syncing it across computers and devices for reference from multiple location.
Notational Velocity
NV is an app with a simplistic approach to usage with some kick-ass features. Its primary focus is that you’ll just search, if found, it goes there else creates a new note if required. The content is compressed and encrypted (optional). Once you got used to the few keyboard shortcuts, you’ll feel at ease with your keyboard and mouse interaction is not needed for most of your task. There is no concept of “Save” in NV, its just saves as you type.
How does it work
You just type in the search area. Press return to add a new note with that title. While you type, NV searches for notes whose body or title contain your words. Observe that naming a note and searching always occur simultaneously.
When you select one of the found notes (e.g., using the up/down keys) NV displays its body in the lower text area (what you’re reading now). If you had typed the beginning of a note’s title, NV would have selected that note automatically.
Just try and get used to few of the keyboard shortcuts and you’ll be all set. Most of them are pretty similar to what you do everyday, like going to the search/address bar in your browser (Firefox, Chrome)
Synchronize natively with Simplenote
The latest addition that made NV a super note-taking app is its ability to sync with Simplenote. Simplenote (view it in iTunes) is a simple to use, free note-taking app for the iPhone.
Open Source
Notational Velocity is Open Source and is distributed under a modified BSD license. It is currently hosted on github.
You can get the source;
$ git clone git://github.com/scrod/nv.git
Download/Install
Visit Notational Velocity and Download the NV.

Personally, I would not term myself an advanced Mac user, far none an experienced one. However, I’ve been very enthusiastic about the Mac lately and have been minutely observing many of the cool aspects of the