Just in case anyone is wondering which one to download based on their USB-Based Microcontrollers (MCU):

For AT90USB162
Download Teensy 1.0

For AT90USB646
Download Teensy++ 1.0

For ATMEGA32U4
Download Teensy 2.0

For AT90USB1286
Download Teensy++ 2.0

For BlackCat USB
Download Teensy 1.0

For AVROpendous v1.1
Download Teensy 1.0

For ATMEGA32U2
Download Teensy 1.0

For AT90USB1287
Download AT90USBKEY

Others
Olimex AVR-USB-STK Backup enabled plus LED Patch
psgroove_ATAVRUSBRF01_patched.hex.gz
psgroove_usbtinymkii_patched.hex.gz

Updated: PSGroove v1.1 Patched with no Backup Manager

입맛에 맞게 골라 드세요(?)