Easy:
MAX7221 - SPI 8 digit LED
- https://mbed.org/components/MAX7221/
- 
SCA61T - inclinometer SPI
- https://mbed.org/components/SCA61T-Inclinometer/
DS1721 - i2c temperature/thermostat
- https://mbed.org/components/DS1721/
MPL3115A2 - i2c altimeter
- https://mbed.org/components/MPL3115A2/
- http://www.ebay.co.uk/itm/Barometric-Pressure-Altitude-Temperature-Sensor-I2C-MPL3115A2-/221499210102?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item339261b976
TEMT6200 - Ambient light sensor
- https://mbed.org/components/TEMT6200/
CMPS03 - i2c digital compass
- https://mbed.org/components/CMPS03-Digital-Compass/
- http://www.ebay.co.uk/itm/Magnetic-Compass-CMPS03-/221437925374?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item338eba97fe
- http://www.robot-italy.com/it/cmps03-robot-compass-module.html

Medium
E-ink sharp 1.3" LCD
- https://mbed.org/components/13-SHARP-Memory-LCD/
LCD-S401
- https://mbed.org/components/Lumex-LCD-S401/

Hard:
RA8875 - 480x272 SPI 4 wire
- https://mbed.org/components/RA8875-Based-Display/