1MΩ Voltage controlled resistor?

Is there any good way to hook up a fairly wide range voltage controlled resistor circuit? So far, I've considered FETs and OTAs. I only have chopper FETs on hand and the datasheet does not list the Pinchoff Voltage. The OTA resistor setup still seems confusing to me. 

These will be used in a Voltage Controlled Oscillator circuit. 

Any ideas? Am I on the right track?

The FETs a classic, and simple method. Just use a standard Jfet. This is one of the best references I know.

You COULD mung somehting from an LDR and an LED as well