gistfile1.txt

linode:~# free -m
             total       used       free     shared    buffers     cached
Mem:           488        427         61          0         31        209
-/+ buffers/cache:        186        302
Swap:          511         14        497
linode:~# 

I contacted Linode about this.. here is their reply:

Thank you for contacting us. When you run the "free" or "htop" commands, the memory that is reserved for the kernel is hidden from view. You can rest assured that you still have the full 512 megabytes of memory, however the amount that is not being shown is simply being used for the kernel.

I hope this clears up any concerns you may have had. If there is anything further we can assist you with, please do not hesitate to let us know.