Here at marxy.org I make printed circuit boards using the rather low-res iron on technique so I went looking for a single sided board design with no fine tracks. For example I can't reliably run a track between two IC pins.
Please correct me if you can, but I couldn't find a design out there so here is my contribution.
The circuit is a minimalist design, the chip runs without a crystal. I find this fine and given that ATMega8 series chips ship with their fuses set for the internal oscillator I'm surprised that more people don't do this for non time critical applications.
Aside from four links, there are only a few components: 10k resister on the reset pin to +5v, a 100nF capacitor across the power rail, and a 1k and LED on the power to show that the board has power. So the LED and 1k resistor are optional.
I bring out all 8 lines of Port D and some spare ground connections along a board edge, Port C 0-5 are also available as are Port B 1 and 2. The pins used for programming go to the standard 6 pin header.
The square pins are pin 1.
There is a PDF version of the design here.
I laid out this board in OmniGraffle and the file is here.
You are free to use this design for whatever you want and hopefully improve on it. I did find some great PCB designs out there but they are all both double sided and often have very fine tracks which are beyond my home fabrication capabilities.