Interesting
The ...Nd7 Trap

The same combination of a knight on f3 and a bishop on c4 can wreak havoc even when Nc6 is played and the queen is not smothered, as in our vote chess game "Serra"
http://www.chess.com/groups/forumview/vc---serra---engine-analysis

I mostly try h6 or e6 when I see that bishop and knight hanging back there.
h6 solves the problem that attacking your fianchetto'd position becomes a lot harder. g5 is a weak square for black a lot of time.
The ...Nd7 Trap arises after
1.e4 g6 2.d4 Bg7 3.Nf3 d6 4.Bc4
when 4...Nd7 looks like a perfectly normal developing move. However 4...Nd7 blocks the bishop's protection of e6 and much worse; it smothers the queen.
Here are six examples.
Arnason vs Pribyl 1990
Santasiere vs Byrne 1946
Srebrnic vs Motoc 2007
Djordjevic vs Trickovic 2012
Maia vs Pereira Vilalba 2001
Hughey vs Day 2001