For you newbies out there, every network interface card (NIC) has its own unique identifier called a MAC Address. How to find your MAC Address. A MAC Address is made up of 6 bytes. The first 3 bytes (6 characters) identifies the vendor. You may need to one day know what vendor made the card based on MAC Address. Of course, MAC Addresses can be spoofed, but the items below will come in handy anyway:

Vendor Lookup by xx:xx:xx:
http://standards.ieee.org/regauth/oui/index.shtml
http://coffer.com/mac_find/

Download the entire public OUI listing:
http://standards.ieee.org/regauth/oui/oui.txt

Don

PS - But how do I change / spoof MAC Addresses? Here's a little extra tidbit for you...

There's a manual way in Linux, and there's macchanger  

Macchanger also supports listing Macs and thereby also vendors. With some one-line CLI kung-fu you can easily find a vendor like Echelon, etc  

Note: It is also possible to do a reverse lookup with macchanger, just use the first 3 (hexadecimal) bytes and you'll be good!