From the 4E DMG...
Corridors
1: Straight 4 squares
2: Straight 8 squares
3-5: Ends in door
6: Straight 4 squares, door on right
7: Straight 4 squares, door on left
8: Straight 4 squares, side passage on right
9: Straight 4 squares, side passage on left
10: Three-way intersection ("T")
11...