My USBTinyISP (with an ATTiny44)
Available from OSH Park here: https://oshpark.com/shared_projects/ijclv4pr
BOM Is pretty cheap. Check the kicad folder for more info. The file is called tinyispmicro.lst.
Firmware is slightly modified from the regular USBTinyISP.
I recommend flashing using the .hex file provided in: firmware/spi/main.hex.
Flash the AVR by conneting the "PGM" pin and another programmer.
Don't forget fuses!!!
Once flashed, disconnect the "pgm" option and connect the "REG" option.