YourDuino MegaNano2560 - Most advanced Arduino Compatible!

See it here:

Running out of memory, I/O pins, UARTS or PWM channels??

Overview

YourDuino NanoMega2560 is a microcontroller board based on the ATmega2560 which is a Microcontroller chip from the same family as the ATmega328 in most Arduinos. This Arduino-compatible board is derived from the Arduino Mega 2560 with changes for a small form factor, flexibility and functionality. It has an amazing 70 digital input/output pins (of which 14 can be used as PWM outputs), 16 analog inputs, 4 UARTs (hardware serial ports), a 16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a reset button. Simply connect it to a computer with a USB cable or power it with an AC-to-DC adapter or battery. The NanoMega2560 is compatible with most shields designed for the Arduino Duemilanove or UNO. Here are some if it's characteristics:

Smaller (30% smaller) and flat form factor
All IO pins are available on connector.
Reset button repositioned easy access
2.54mm alighment for proto boards compatiblity
3.3V or 5.0V selectable
Auto/Manual reset selectable
Full featured USB Interface , connections for "Bitbang" are accessible.
Uses the FT232RL VS ATmega8U2 of new Arduno UNO 2011: maybe be more reliable.

Many other low-cost Arduino related products also at YourDuino.com