If you like Arduino boards and the IDE, but you need more I/O or memory, the Mega2560 might be for you. With 54 digital I/O, 15 of them PWM capable, and 16 analog inputs, you won't run out soon. There is a 256kB flash, 8kB RAM, and 4kB of EEPROM. If you have been working within the confines of the ATmega328 or ATmega32U4, this board will look like a mainframe.
The Arduino Mega 2560 is not without it's quirks, though. For instance the pins the Uno might use for software serial communication may not support pin change interrupts on the Mega2560 (D7 & D8). The processor uses a 3-byte program counter, so it is a bit slower than the smaller Arduinos.
|Arduino Mega 2560|
|Test Current Draw||90mA|