Update 09.02.2016
The latest NirvanaHQ update made this userscript both obsolete and deprecated.

There are tons of tools for time and task management out there. After trying out some of them I decided to stick to NirvanaHQ. Using IFTTT I forward all of my virtual inboxes except emails to NirvanaHQ. I no longer have to check my unseen YouTube videos or new Soundcloud uploads. I find them all in one system and process them regularly.

I have written a little userscript, which adds a “Hotkeys” button to the top menu. It opens a popup window, containing all the available keyboard shortcuts. I find it useful, to quickly look up some hotkeys.
You can get the latest version at GitHub.

NirvanaHQ Userscript