The following resources have been mentioned in blog posts.
The War of Art; Break Through the Blocks and Win Your Inner Creative Battles, Steven Pressfield (Amazon Kindle link)
The Miracle Morning; The Not-So-Obvious Secret Guaranteed to Transform Your Life (Before 8:00am), Hal Elrod (Amazon Kindle link)
The Creative Penn – Joanna Penn writes fiction and non-fiction, and has lots of wonderful information on her site, including her weekly podcasts.
Evernote – the app that creates a workspace for everything you do. An essential tool.