Is it possible with a Seeeduino to control 4 electric motors?
Yes. Elaborate?
/me
go ask in the seeduino forum 
ahha
Hi, sorry.
I have four electric motors and I want to be able to control all four but at different speeds, so rather than just have pins 0-3 set to HIGH so that all four motors run at once, I would like to be able to run one motor at say, half speed, one at full speed, one at 10% and one at 25% - just an example obviously, these values would change of course.
I am assuming I need analog output to control these?
You can use the Arduino's PWM outputs to control motor speed. It's not true analog, but it simulates an analog output by switching on and off rapidly. The software side of it is the 'analogWrite()' function.
That sounds like what I'm after - so it is possible to control 4 at a time?
Yes. The Arduino Duemilanove (which I guess you're using) has 6 PWM outputs (3, 5, 6, 9, 10, 11)
Just don't expect to connect the motor directly to the PWM pin on the Arduino. The arduino can output 40mA on a pin at 5 volts. Cheap low voltage motors usually start at needing about 2,000mA, and decent motors usually need at least 12 volts.
You'll need a driver to connect between the seeeduino and the motor.