Hackaday reports on an open source project from developer Ryzee119 that uses a Teensy board and allows a variety of USB controllers to work on a Nintendo 64 console.
The project allows for virtual Rumblepak and Memorypak storage, and even allows uploading of data like ROMs for emulators via the tool. So far the project supports a number of 8BitDo, XBox360 wired and wirelss and Raspberry Pi Interface controllers, with more planned.
Plenty of great features are already in the list, such as dual-analogue-stick input for GoldenEye, N64 Mouse support, and configurable dead zones for analogue stick calibration and customisation.
As a separate but related project, Ryzee119 also includes a test ROM for N64 to test, calibrate and configure your controllers.