Can the URL check return the Certificate details (if HTTPS). I like to check and monitor the Certificate expiry date, Serial number, and common name on some servers.
Also it would be very useful to do a CRC/hash check on the page returned to monitor if the pages changes and/or check if the page contains certain text in the html. i.e if "hello world" is somewhere on the return page, then return ok else return error as a tag field.