NewGRF

NewGRFs are graphics and mods you can use to make your game look different, or add more things like station tiles and industries. There is an extensive list of them, and they all add all sorts of new goodies to play around with. Off of the forums, you can find more NewGRFs that other users made.

Downloading
There are two ways to download NewGRFs. You can use the in-game installer, or use external sources.

In-game Downloading
Go to the main page, and press NewGRF settings. Then go to the "Check Online Content" button, which should bring you to a screen like this: From here, you can search all of the online content, all you want. Select the content you want, and then press download. After the pop-up says "Download Complete", press the Okay button which should take you back to the settings page. Select the content you want, then press "Apply Changes". If you want, press the save preset, and give it a name, or if you just want to test it out. Start a new game, and the changes should be there!

External Content
Some NewGRFs may not be available in the Online Content section (for example, the NewStations GRF) but can be downloaded externally. You can search here for any NewGRFs you want, or off of the forums. Once you find the one you want, follow the instructions to download it. Once downloaded, move the file into the newgrf folder in the game file.

The NewGRF should now be in your list in the settings!

List of NewGRFs
List

This is an incomplete list, and there may be more.