MaxMem (free) promises to make the most out of your RAM by regularly releasing memory that your system no longer needs. In that way, it says, it ensures that your PC and programs get the maximum amount of memory they need, for top performance. "It says...?" asks the skeptical reader. Read on.
MaxMem monitors your system, and when your free memory reaches a certain low threshold, it automatically frees up memory. You can set the thresholds, and also tell the program how aggressive it should be about managing your memory.
There's a fair amount of controversy over whether programs like MaxMem really work or are needed, because Windows over the years has gotten much better at memory management than it used to be. In my tests, I didn't find that the program sped up my PC, which is a Quad Core PC running at 2.4 GHz and with 2 GB of RAM. And when I told the program to use its aggressive mode, the situation worsened: My programs became slow and unresponsive.
However, MaxMem may perform differently from PC to PC. Given that it's free--and that it uninstalled cleanly from my tester--you might want to give it a try. As the saying goes, your mileage may vary.