These are commands that I use on occasions, but always seem forget.

show int phy-id (see stats of port)
show arp (show current switch ip)
show int trunk
show mac-address-table
show mac-address-table address 0000.1111.2222
show vlan
show cdp neighbors detail
show cdp neighbor PORTNAME detail
show switch (list switches in stack)

From TFTP:
copy tftp: running-config
copy running-config tftp:

This command is useful to find out if any pairs are open. Just connect a device to the other end, and run the command:

Switch#test cable-diagnostics tdr interface g1/0/2
TDR test started on interface Gi1/0/2

It may take a few seconds to run. Then issue the following command:

Switch#show cable-diagnostics tdr interface gigabitEthernet g1/0/2
TDR test last run on: Oct 12 07:12:12

You should see some results like the following:

Interface    Speed    Local pair    Pair length    Remote pair    Pair status
---------    ------   ----------    -----------    -----------    -----------
Gi1/0/2        auto     Pair A        22 +/- 4 m         N/A       Open
Pair B        21 +/- 4 m         N/A       Open
Pair C        5 +/- 4 m          N/A       Open
Pair D        20 +/- 4 m         N/A       Open