Fluffy Manager 5000 is a mod manager for Resident Evil 6, which lets you do stuff like:

• Make it easier to install and uninstall mods.
  
• Trainer functionality (teleport players, walk through walls, change voice type, load any stage, host 6 player mercenaries, add AI controlled players, and many other features). It also has optional network capability, so you can play multiplayer with other people using the trainer and all changes will remain in sync.
  
• Jukebox! Rock out to memorable tunes like bgm0101!
  
• Also compatible with Resident Evil 4, Resident Evil 5 and Resident Evil: Revelations. Functionality varies depending on the game. RE6 has the most stuff available.

Download link: https://www.fluffyquack.com/tools/modmanager.rar

You can find more information about the manager at this link: http://residentevilmodding.boards.net/thread/507/

Remember to read the readme.txt to learn how to set up the manager.

If you need help, post a reply in the above linked thread or leave a comment to this guide.

What's a mod manager without mods to install?

Here's a video showcase series showing off various mods along with download links: https://www.youtube.com/playlist?list=PLMyoprrqVo6APdpMVkhefHTRn-94umhDn

A few example mods for RE6, RE5 and RE: Revelations:

Ada Business

Boss Mania - Public Assembly

Jill Business

To find even more mods, you can check out this modding community: http://residentevilmodding.boards.net/ (Note that not all mods found in this forum are directly compatible with Fluffy Manager 5000, so you might need to do some extra work to get some mods running.)