LOL, THIS IS NOT A MEM LEAK! this is good that you ram is used up!. THIS IS NOT WINDOWS.
Linux uses a cache,
type top and you will see it!!
Mem: 515164K av, 347116K used, 168048K free, 0K shrd, 9184K buff
Swap: 1028152K av, 0K used, 1028152K free 230180K cached
look at all that cached, and look at my used and my av.
this is normal to have verry little "FREE" ram.
if someting needs the ram it will get it, but till then it sits in the cache, and so apps that have benopen befor will open again but faster , insted of pullin from the HD it will pull from the cache (ram)
this is noraml not a problem.