You could also write yourself a little script that does a wget whatever.com/lala.htm , and then does some greps or regex matching on the downloaded file. This is a terrible example that might not work but it should give you some ideas:
grep "website title" mypage.html
if -z $result
echo "omg no title found! good!"
echo "zomg bad page!"
With an exit code of 2, nagios will throw a crit. 0 is OK. You could of course make this waaaaaay more robust