This geeklet displays the top 12 processes sorted by their memory usage. It updates every 30 seconds.
The three columns it shows are given by "command %mem %cpu." You can delete one of those if you don't want it. You can change "head -13" at the end of the command to specify how many processes to show.
ps -amcwwwxo "command %mem %cpu" | grep -v grep | head -13