This is an alternate url-checker wich works analog to check_http but which checks destinated url for valid xml if necessary.

You can download it at nagios exchange here or locally here: check_url_state.pl

Update (Apr 2013):

I’ve found a bug: if you want to check content on a non-existent host my script doesnt recognize that the host doesnt exist. I’ll fix it asap but due to lack of time this may take a while.

Update2 (Aug 2013):

The Bug mentioned above also occurs if you recieve a timeout to your Get-Request. I’ve already had a timeout but not a check if an error occurs.  So I only have a bad workaround but no proper fix yet.

In Both cases (invalid/unexistand host AND timeout) you recieve something like “Status .” with a WARN-Message.