In addition to (or instead of) having to specify that a post is NSFW in the thread title, the addition of a message icon to the list available when you create a new post might be a good idea.
Perhaps similar to the yellow exclamation icon, except in red.
as in:
or:

The_Spectre 2004.05.05, 08:06PM — NSFW Post designation (suggestion)
StinkFist 2004.06.17, 09:03PM —
yeah, I guess I didn't get to it "when I got home".
I'll try to do it this weekend 
StinkFist 2004.10.16, 12:44PM —
Nope, "politician". I only said that I would try.
I tried and tried but I couldn't.
then I wept for hours and hours and whours and whores and whors.
first



