There are lots of instances where Nightcrawler (and others) used an image inducer to disguise their appearance. Here are just a few:
X-Men, Vol. 1 #98: Merry Christmas X-Men--The Sentinels Have Returned!
Kurt disguises himself as Errol Flynn while in NYC.
X-Men, Vol. 1 #101: Like a Phoenix, From the Ashes
Kurt disguises himself as Errol Flynn again.
X-Men, Vol. 1 #103: The Fall of the Tower
Kurt tricks Juggernaut by disguising himself as Professor Xavier.
X-Men, Vol. 1 #107: Where No X-Man Has Gone Before!
Kurt disguises himself as an alien beast. (I think this might be the first issue where Kurt teleports with another person, but I'd have to check on that.)
Classic X-Men #4/2 (Dec. 1986): The Big Dare
Wolverine challenges Nightcrawler to walk down the street without his image inducer. Before this, Kurt was too nervous about how others might react to his appearance to go anywhere without his image inducer, but after this he starts to give it up and eventually abandons it except in case of emergencies. This issue is also the real start of Wolverine and Nightcrawler's friendship.
Wolverine, Vol. 3 #6: So This Priest Walks into a Bar...
Kurt disguises himself as a priest. He and Wolverine have a heart-to-heart over some drinks.
Hope this helps!
[Edited on 24/8/2010 by Rowena]