300998 http monitoring script

looking to start a free website monitoring service. Will need a simple site (header of 100 pixels high 800 pixels wide) and body of site 800 pixels wide. Site shoudl have a member login system and registration page with username, password , website url, etc. Members should be able to edit their info. member control panel should allow them to add 5 urls to monitor. I want ability to change this to any number. If site is down, must send them a email. when site is back up after being down send them another email. Also woudl like to store that info and send a weekly report. If it could do other things already (ftp, email, dns..) that woudl be nice too... but not necessary Someone has to have this already done no?