Open Multiplayer
A multiplayer mod for Grand Theft Auto: San Andreas that is fully backwards compatible with the existing multiplayer mod San Andreas Multiplayer.
This means the existing SA:MP client and all existing SA:MP scripts work with open.mp and, in addition to this, many bugs are also be fixed within the server software without the need for hacks and workarounds.
If you're wondering how to download, or how you can help contribute to the project, please see this forum thread for more information.