I have a temperature controller and have used that with a fridge for fermentation control. Works very well, although it isn't always easy to get your fermentation temps dialed right in within one degree.
IF your basement is already cool (say 15 degrees C or lower -- note this is a BIG requirement), there is a much easier (and cheaper!) method that I greatly prefer. Get yourself a big Rubbermaid tub ($7) and a 50W or 100W aquarium heater ($15-25). Fill the Rubbermaid about 3/4 full with water and use the aquarium heater to get the water to the temperature you want. It will keep the water temp very stable, and the control is very precise (since many fish can't tolerate big temperature swings). Get this set up and equilibrated to the temperature you desire a couple/few days before you brew.
There are two big advantages of this approach, IMO:
1. You have very precise temperature control with the water bath, and it is dead easy to do things like start on the cool side for the fermentation then gradually ramp up the temperature towards the end (say for a Belgian strong ale that you really want to attenuate out).
2. The water bath absorbs all the temperature fluctuations, either from the heater or from the heat generated by fermentation. One issue with a fridge is that if you have a fast and violent fermentation, often the fermenting beer is many degrees above the ambient air temperature inside the fridge (the beer is generating more heat than it is losing to the air). In a water bath, this doesn't happen because the water bath absorbs a lot of that heat. This keeps your fermentation temps much more constant and really makes a big difference in the finished beer.
Note that obviously this method works well for ales, but won't help for lagers.