Calls to mind a long forgotten, and perhaps one of the most useful bash scripts I've written which addressed this issue in a very rudimentary way; Curl a url, hash the result to file, compare the current hash to the saved hash from the previous run and generate an email on diff.

My goal was to monitor the online release of tickets for the 2009 Scion Rock fest (luckily no js, or even Adobe Flash[!] in use), and it worked brilliantly to that end.

[grammar]