Electrum (from 2.7.0) features native support for Nano S (Linux, Windows, OS X).
Download and install Electrum from the official site.
Select Standard wallet
Connect your Nano S to your computer, enter the PIN and select the Bitcoin app.
Then select "Use a hardware device"
Your Nano S is detected
Press Next, and select your Account Number. If you are not sure, leave the field with 0, otherwise enter the index of the account you want to import.
Click on Next, and Electrum with sync your account. Depending on your connection and the server, it may take from a few minutes to half an hour.
Once the sync process is finished, you can use Electrum normally.
Sending a transaction
When you want to sign a transaction, you must validate it on your device (Nano S).
Important archlinux user note:
installation of python2-btchip is required to detect the Nano S
Important Ubuntu user note:
These additional steps are required on Ubuntu 16.04
apt-get install libusb
apt-get install libudev-dev
ln -s /lib/x86_64-linux-gnu/libudev.so.1 /lib/x86_64-linux-gnu/libudev.so
pip install btchip-python