WoW Model Viewer
Ladik's MPQ Editor
My Warcraft Studio
DBC Editor
EDIT2: You can see display IDs in wowhead.
Ex: Go to http://www.wowhead.com/?item=45801 , click on View in 3D, the URL will modify to "http://www.wowhead.com/?item=45801#modelviewer:1:28953:0"
28953 is the ID. So you don't have to find it in WoWModelViewer or something like that...
HOW TO: TITLE CHANGE
HOW TO: CREATURE/MOUNT/N-C PET CHANGE