I've written an Android app and a couple of Chrome extensions, mainly to fix my personal bugbears, but they're available to the public. The source code is also on Github.
Get the times of the next trains for your underground station on your wrist, as well as line status and the last train of the day.
Rename any tab quickly and easily, in a simple, lightweight extension. Optionally, you can 'lock' a title to a tab until it is closed.
Fellow Cambridge student? It'll rename most of your resources for you, including CamTools.
Hate clicking a link to a YouTube playlist, and getting the extra playlist clutter? One click and it's gone.