Some places I like to go to for inspiration. In no particular order.
Ben Evans: Ben writes one of my favourite email newsletters on tech.
Mobilisation Lab: A fab place for the latest in digital mobilisation & campaigning.
Osocio: A place to find the best of non-profit advertising and marketing.
The Sell! Sell! Blog: A sometimes ranty, often sweary dose of common sense.
We Are Social: A fab blog full of great opinion and data.
I also write on Medium. Here.