Why is my device not utilizing all of its available RAM? I have a Nook Color with Cyanogenmod 7.2 (on mSD), and Nook Color is supposed to be 512MB of RAM (says so on product's page).

When I open Menu (on bottom bar, while on desktop) > Manage Applications > Running, it says on the bottom left 95MB used, and on the bottom right it says 174MB free. These are about 270MB, does that mean my RAM is corrupted? Why is it not utilizing all 512MB of RAM?
Although your device may have 512 MB of RAM in it, the settings almost always report the RAM that is available to user processes, not all of the physical RAM. This means that it won't report any memory that is being used by:


Android's system-level processes
Your GPU, which often uses shared memory
Any memory a cellular radio chip may need to function (irrelevant in your case)


Although this memory is not reported, it is being used by the system. Reporting it in a system monitor is simply not very relevant because the OS is going to basically keep it for itself forever (after all, the OS needs RAM to run properly, too). There is really no way that you can get this RAM "back" from the system, but you wouldn't want to anyway since your phone would basically stop functioning without it.