You can monitor when your favorite web pages are changed. The following sites will monitor specified web pages, and send you email when the pages are updated with new information:
With older Netscape web servers you could also determine when a web page file was last modified with the about feature by entering “about:URL” in the location field which then returned an information page. This feature was useful for comparing the dates of pages to check how old a page is, or for checking the time-stamp on news pages of various news services when checking late breaking news stories. However, unfortunately few web servers now support this feature — we can only hope it will someday make a comeback…