nvpy is a notational velocity like notetaking application which syncs with simplenote.
To get going:
sudo apt-get install python python-tk python-pip python-markdown
sudo pip install nvpy
Then create a .nvpy.cfg file in your home directory with following structure:
[nvpy] sn_username = simplenote_username sn_password = simplenote_password
(Substitute your simplenote username and password!)