bulk page update date checker!?

When I want to check when a page has been updated I type in the browser address:
javascript:alert(document.lastModified)

Is there a tool to do this automatically for a list of web pages! this is important!
for example:
You scrape proxy sources, you wanna know which ones are updated, bang check web pages update date and here they are!
so if you know any tool that does this please report back

for future reference, software is called website watcher