hi ,
im an avr developer and instructor i have a frind of mine that has a programer that works with the serial port (spi) it programs more than 45 devices (At90s , Attiny , Atmega , At89s ) including Atmega8535 (the hardest in the family)
he also made a great tutorial for begenners and experts to make you master avr with assembly programing (for all the internal periphirals, lcd stepper motor and other externals )
but these things are for sale so if you want them contact me and i will tell you more details.
thanks