Memory Information of different OS platforms

As a DB admin, sometimes it's necessary to check the memory information of the server. So here I provide some simple commands that would give you the information of the memory in the server for different OS platforms...
Note: All the commands are standalone and gives output in a different variety

AIX

lsattr -El sys0 | grep realmem
prtconf

LINUX

free
cat /proc/meminfo
dmesg | grep Memory

HP-UX

vmstat 5 5
swapinfo -tam 
glance # hit m for memory info

SOLARIS

/usr/sbin/prtconf | grep Memory

WINDOWS

Click Start --> run --> enter "dxdiag" to find system information.

Please add comments if I miss something...