WebUp

From Design Lynx:

Keep an eye on your site. WebUp monitors your web sites to ensure they are accessible to the Internet populous. It does this by periodically checking the web site for an error, if an error is found the user can be warned in a number of different ways, from emailing web site administrators to dialog prompts to a simple system tray notification.

ebUp can be scheduled to check your web sites in intervals ranging from 1 minute to 24 hours.

WebUp's daily report records every check allowing you to look back over the previous web site checks. Reports can be saved automatically or printed at any time.

WebUp's status graphs allow you to see the frequency that your web sites are failing, a HTML version can be generated so you can print daily, weekly, monthly (or whenever you need to) reports.