There are 3 repositories under roller-coaster-tycoon topic.
Repository for translation and discussion for OpenRCT2.
A plugin for OpenRCT2 that lets you edit vehicles on any ride in your park on the fly.
This plugin lets you quickly cover guide paths with full paths without changing the guests pathfinding.
RollerCoaster Tycoon Randomizer mod for RCT1 and RCT2 inside of OpenRCT2
Official OpenRCT2 project website.
A plugin for OpenRCT2 that spices up the multiplayer aspect.
Plugin for OpenRCT2 to edit rides based on colour schemes.
This plugin for OpenRCT2 allows you to add/delete messages in the park.
Parse OpenRCT2's NSF *.park file (Work in progress yet)
A plug-in for OpenRCT2 that allows you to increase (or decrease) the cost of various expenses, such as staff wages or ride upkeep
Extracting resources from Roller Coaster Tycoon
Every roller coaster I have built in RCT2 for iPad