I would like to use arduino to interface a light/photo sensor and a weight sensor with a PC (real time data collection). I noticed a few links from various light/photo sensor projects with arduino. I could not locate any projects with a weight/load sensor. I'm considering using FlexiForce Load/Force Sensors and Systems | Tekscan as the load sensor. Cost is an issue for both sensors (each less than $20 per unit). Any advice or links regarding implementation would be appreciated. Thanks.
Not sure exactly what you're looking for, the sensors you've linked to might work for what you need but without further information on exactly what you're trying to measure it's tough to help.
Keep in mind that with these force sensitive resistors you have to account for the area that you're applying the load over, if you have a resistor and you're only using 1/10th of the surface area you'll have diminished precision.
Sparkfun warns us that they're not very accurate but good for detecting contact/squeezes but not really forces.
Have you looked at strain gauges? You have to set them up with a bridge and calibrate them but they'll be much more accurate depending on what you're doing.