ps -e -o pid,vsz,rss,comm= | sort -n -k 2
The above will show you the process id, how much memory is allocated to a process, how much the process is actually using, and a comment of process description. It will then sort by how much memory is allocated to a process for you to see which apps are using up a lot of VSS.
Long running processes are useful to know as well when looking for memory hungry apps that have been running a long time
ps -ef --sort=start_time