Let's take a look at the mbed NXP LPC1768 Microcontroller!
This diagram shows the commonly used interfaces and their pinout locations. Note that all the numbered pins (p5-p30) can also be used as DigitalIn and DigitalOut interfaces. Some pinout options are not shown here; for a full details, see the technical reference for the full pinout specification
The microcontroller I/O is all 3.3v logic, but 5v tolerant. A digital pin can drive 40mA, up to a total of 400mA. For full details, see the Technical Reference.