Bloglines has announced that it will begin offering package tracking
I think this is a great use of RSS. A few months ago, Ben Hammersly released a PERL script that did the same thing, but only with FedEx. It also had to do a screen-scrape and pull the information out.
I actually used it to track a package and it was nice not having to go through the hassle of visiting the site, entering the tracking number and waiting for the detailed status to show up (which was usually two clicks away anyway). I could just let my RSS reader run and when the status was updated, I was updated.
I am assuming that Bloglines got ahold of some sort of developer API to be able to run a service like this, but it is still great. Even better than having the status e-mailed to you.
I addition to tracking packages, you can also use Bloglines to track items in Yahoo!Groups and Google Groups.