Basics:
call calls a batch file from another one
cd change directory
cls clear screen
cmd start command prompt
color change console color
date show/set date
dir list directory content
echo text output
exit exits the command prompt or a batch file
find find files
hostname display host name
pause pauses the execution of a batch file and shows a message
runas start a program as another user
shutdown shutdown the computer
sort sort the screen output
start start an own window to execute a program or command
taskkill terminate a process or a application
tasklist display applications and related tasks
time display/edit the system time
timeout wait any time
title set title for prompt
ver display operating system version
w32tm setting time synchronisation/time server/time zone
Network:
ftp transfer files to a FTP server
ftype display file type and mapping
getmac display MAC address
ipconfig display IP network settings
netsh configure/control/display network components
netstat display TCP/IP connections and status
nslookup query the DNS
pathping test the connection to a specific IP address
ping pings the network
route display network routing table, add static routes
systeminfo displays computer-specific properties and configurations
telnet establish Telnet connection