Here’s a pdf document with some basic Cisco router commands. For the pro’s this might be already known, however for starters with Cisco this could be very handy.
Download : http://www.lamnet.nl/wordpress/wp-content/uploads/2007/12/basic-cisco-router-commands.pdf
Here is a chart of the OSI and TCP-IP model. This could be handy if you’re in the CCNA/CCNP course, or just as a sysadmin.
Download : http://www.lamnet.nl/wordpress/wp-content/uploads/2007/09/osientcpipmodelextended.xls