As much as possible avoid meta-discussion such as "look into yourself what you wanna make".

▶ Online video editor integrated with YouTube: [Desktop Electron app] Make editing videos as easy as watching them.

▶ Visual PHP code editor, focused on Wordpress plugin development: [Web-based] Similar to Unreal-Engine-Blueprints.

▶ Twitter-like social network for fairly smart people. [Web-based + mobile app] A social network that asks its users very simple basic intelligence questions, things like “Chocolate milk is usually made of: A) Milk from brown cows B) Cocoa and sugar C) Milk and cola”

▶ Online Webcomic creator [Web-based]: Make creating webcomics easier (pre-made cartoon eyes, noses, backgrounds, etc)

▶ Make your website prettier and responsive without pain [Web-based]: Analyze an old website visually, create a more modern look for it, and a responsive version using algorithms.

▶ GTA2 like game [Windows/linux and mobile]: Made using Unity, cartoony style, think Crash-bandicoot meets old GTA. Plus cartoony power-ups think Rocket League.

There is character limit here, so an extended version with the rationale for each idea may be found at:

https://gist.github.com/Ivanca/ab07fe09da06bb91974a54dd1f283ffa