Spent a few hours this morning building the USBtinyISP AVR Programmer from adafruit.com. Very happy to report that it went together easily and worked the first time out. Awesome! I did make one small blunder though. I should have read through the installation instructions before starting. You are supposed to put the LEDs one half inch over the pc board. I mounted them flush to the board, and now you have to look down into the enclosure to see them. I'm hoping a little work with coffee stirrers and perhaps a little hot glue can remedy the situation.
The online assembly instructions are very good. I did wait to install R7 as suggested and I was glad for it. One change I would make is to put the USB jack on after the 6 and 10 pin headers. The headers have a lower profile and I had to prop them up on something when I soldered them. Also, my kit had a smaller C2 100 microfarad capacitor than in the instructions. It fits in beside the '125 buffer chip so I didn't bend it over the '125.
After it was all assembled I turned off the solder iron and downloaded the Windows drivers. The USBtinyISP runs as an actual USB device and not as a serial port emulator, so for AVRDude you just use "-c usbtiny". That's a lot nicer than plugging in the Arduino and then trying to figure out what COM port it got. I connected it first to a project I have installed on the Evil Mad Scientist MegaXX8 target board but that didn't work. I'll have to sort that out later. Next I connected it to the six pin port on an Arduino. This time it connected and read out the device signature just fine. Last I hooked it up to a Larson Scanner I built with a Tiny2313 chip. Read that one also. This is so cool, now I have an AVR programmer that I can just plug in and use!