The "Category" search field should include a drop-down menu.
The "Category" field on the Dashboard or in Edit Stream Info should include a drop-down menu that lists your recent and most-frequently streamed titles. It's cumbersome to search by text every time you switch categories and there's currently a frequent bug in which updating your Steam Info will revert back to your previous Category if you're not paying attention, so you effectively have to enter the field twice.
It would be great that twitch could detect our most used games and autosugest them when we enter the game (in the stream settings) that we are gonna use on the stream.
Make buttons that show the common games streamed so that instead of having to type in your game that you're playing constantly, you'll have a small selection of four of your most common games to pick from and a search bar if you need to look up a new game.
Instead of searching for a game that you are playing on stream that you usually play. Make a listing of 5 games or so that you play on stream the most often so you can just click the game option and it auto updates the game you are under.