QOwnNotes is the open source notepad for GNU/Linux, Mac OS X and Windows, that works together with the default notes application of ownCloud.
So you are able to write down your thoughts with QOwnNotes and edit or search for them later from your mobile device (like with CloudNotes or the ownCloud web-service.
The notes are stored as plain text files and are synced with ownCloud's file sync functionality. Of course other software, like Dropbox can be used too.
I like the concept of having notes accessible in plain text files, like it is done in the ownCloud notes app, to gain a maximum of freedom, but I was not able to find a decent desktop note taking tool or a text editor, that handles them well. Out of this need QOwnNotes was born.