squeue

• Lists all jobs in the queue.

sinfo

• Shows which nodes and processors are in use.

scontrol

• Shows more detailed job information.

sstat

• Shows maximum memory use of a job (among other things).

chris@node0:~$ sinfo
PARTITION AVAIL  TIMELIMIT  NODES  STATE NODELIST
all*         up   infinite      4  drain node[5-7,11]
all*         up   infinite      9  alloc node[1-4,8,12-13,15,17]
all*         up   infinite      4   idle node[9-10,14,16]
short        up    2:00:00      4  drain node[5-7,11]
short        up    2:00:00     10  alloc node[1-4,8,12-13,15,17,91]
short        up    2:00:00      5   idle node[9-10,14,16,92]
gpu          up   infinite      1  alloc node91
bigmem       up   infinite      1   idle node92

chris@node0:~$ sinfo -o "%C"
CPUS(A/I/O/T)
78/178/64/352

chris@node0:~$ sinfo -p standard -o "%C"
CPUS(A/I/O/T)
77/131/64/272

This is a script that gives summary information on the number of cores and amount of memory being used by each user, and the number of cores and amount of memory being used on each node.