AVR Development Board

We have about 6 Mega16's and 8 mega48's, along with a number of programmers and an AVR Dragon.

It would be pretty cost-effective to design a simple development board I think. The board could then be populated as needed to make development platforms. What should we have on it?

• 5V Regulator
• 3.3V Regulator
• RS232 (useful?)
• USB to Serial
• Buttons
• LEDs
• Two sockets: one for Mega48 (would also fit 88/168 and others), one for Mega16
• Crystal oscillator

• Size: 100mm x 80mm (we can use Eagle to design it then, which would be free & runs on Windows/Linux/Mac)