What would be the simplest way to check a web page for changes? I want to scan a web page every so often, and compare it to an older scan. One problem is I also need the scan to ignore certain changes, such as the time of day, etc. I only want to check for relevant updates.
I won't write code, but I'll give you the process I'd go through for solving this problem:

Retrieve the source of the page
Replace out all of the parts
of the page that we don't care to monitor
Calculate an md5 or
sha1 hash of the source after replacements are made
Compare the
hash with the stored hash, see if it's different, and do whatever
you need to do if the page has been updated
Store the new hash
Detecting web page updates with python