What am I missing?

66.207.165.166 niggertits.org
98.124.198.1 www.niggertits.org
98.124.198.1 status.niggertits.org
206.220.140.2 ns1.4chan.org
207.126.64.163 team.4chan.org
#207.126.64.164 ???
207.126.64.165 ns2.4chan.org
207.126.64.165 mail.4chan.org
207.126.64.165 yotsuba.4chan.org
207.126.64.166 4chan.org
207.126.64.166 www.4chan.org
207.126.64.166 localvillain.org
207.126.64.166 www.localvillain.org
207.126.64.167 content.4chan.org
207.126.64.168 orz.4chan.org
207.126.64.168 orz.niggertits.org
207.126.64.169 tmp.4chan.org
207.126.64.170 koiwai.4chan.org
207.126.64.171 rs.4chan.org
207.126.64.172 static.4chan.org
207.126.64.175 fuuka.4chan.org
207.126.64.175 jumbo.4chan.org
207.126.64.176 zip.4chan.org
207.126.64.176 zip.niggertits.org
207.126.64.177 bin.4chan.org
207.126.64.178 dis.4chan.org
#207.126.64.179 ???
207.126.64.180 ena.4chan.org
207.126.64.181 img.4chan.org
207.126.64.181 img.niggertits.org
207.126.64.182 img.4chan.org
207.126.64.183 dat.4chan.org
207.126.64.184 dat.4chan.org
#207.126.64.185 ???
207.126.64.186 cgi.4chan.org
207.126.64.186 cgi.niggertits.org
207.126.64.187 nov.4chan.org
#207.126.64.188 ???
#207.126.64.189 ???
#207.126.64.190 ???
207.126.64.191 danbo.4chan.org
209.85.171.121 status.4chan.org

Wow, you've got much more addresses than I ever had, OP.

mail.4chan.org

Of course this is for moot's e-mail and I assume also serves the 4chan staff as well.

yotsuba.4chan.org
koiwai.4chan.org
fuuka.4chan.org
ena.4chan.org
danbo.4chan.org

What's the story behind these addresses?

They've switched hosts again.  Current list (as of 2009-08-02):

204.152.204.152 ns1.4chan.org
#153-161 (no server)
204.152.204.162 mail.4chan.org
204.152.204.163 team.4chan.org
#204.152.204.164 ???
204.152.204.165 yotsuba.4chan.org
204.152.204.166 4chan.org
204.152.204.166 www.4chan.org
204.152.204.167 content.4chan.org
204.152.204.168 orz.4chan.org
204.152.204.169 tmp.4chan.org
204.152.204.170 koiwai.4chan.org
204.152.204.171 rs.4chan.org
204.152.204.172 static.4chan.org
#204.152.204.173 (no server)
#204.152.204.174 (no server)
204.152.204.175 jumbo.4chan.org
204.152.204.176 zip.4chan.org
204.152.204.177 bin.4chan.org
204.152.204.178 dis.4chan.org
#204.152.204.179 ???
204.152.204.180 ena.4chan.org
204.152.204.181 img.4chan.org
204.152.204.182 img.4chan.org
204.152.204.183 dat.4chan.org
204.152.204.184 dat.4chan.org
204.152.204.185 fuuka.4chan.org
204.152.204.186 cgi.4chan.org
204.152.204.187 nov.4chan.org
#204.152.204.188 ???
#204.152.204.189 ???
#204.152.204.190 ???
74.125.47.121 status.4chan.org

IPs marked "???" respond to ping, but domain is unknown.  niggertits.org points to old 4chan IPs and localvillain.org doesn't exist, so forget those.

also, danbo.4chan.org disappeared

I tried the other yotsuba characters, but no luck