A Novel Idea
Price: Free, but $2.99 to unlock some features and remove ads.
Medium: Writing and Coding Programs
Description: An iDevice app (I don't know if there's an Android version or not) designed for planning out novels, but can be used for any kind of storytelling medium, including webcomics. It can organize lists of scenes, characters, and locations for use in your work, and it also asks lot of questions that can help get creative juices flowing. It's quite useful for fleshing out your characters, writing the major events in your story and linking them together coherently, and keeping track of all the elements of your story that you come up with. Basically, it's just about everything you need to outline and organize any creative work.
Pros: Very, very simple to use. Since it's for portable devices, you can take note of any sudden epiphanies you happen to have before you inevitably forget them. And it helps to remind you what sort of information you might need to construct deeper characters and scenes.
Cons: As of time of writing, it's noticeably buggy. It crashes occasionally, and backtracking buttons don't always work the way they should. Some fields are a bit limited too.
Where to find: Apple App Store and if anybody knows about any other versions, please let me know.