This is a ruby script that can download a web page. Source here:
http://code.google.com/p/nagios-check-webpage/
Installation:
Prerequisites:
apt-get install ruby rubygems
gem update
apt-get install ruby1.8-dev
gem install hpricot
apt-get install libopenssl-ruby
Nagios Check Command:
define command{
command_name check-webpage
command_line $USER1$/check_webpage.rb -u $HOSTADDRESS$$ARG1$
}