5 Ways to Monitor Websites
These are sites and software tools that can automatically track changes on chosen web pages and send alerts when a website has been updated with new information. This is especially helpful for monitoring blog sites and other irregularly updated sources.
- InfoMinder
"A hosted [fee based] subscription service that allows you to track changes to web pages, blogs, RSS feeds and wikis." - Google Alerts
"Email updates of the latest relevant Google results (web, news, etc.) based on your choice of query or topic." - SurfSaver
It "lets you save, organize, and search the information you gather on the Internet. SurfSaver is an ideal tool for researchers, packrats, and anyone else collecting information on-line." - Watch That Page
A service that enables you to automatically collect new information from your favorite pages on the Internet. You select which pages to monitor, and WatchThatPage will find which pages have changed, and collect all the new content for you. The new information is presented to you in an email and/or a personal web page. You can specify when the changes will be collected, so they are fresh when you want to read them. The service is free. - Website Watcher
It "detects website updates for you and highlights all changes in the text."
You may also wish to look at versionista.com (hosted/fee-based).
http://www.backtype.com is another good one to add to your list. It picks up blog comments and the like.