Gmail has offered an extremely handy feature for quite awhile that lets you subscribe to an RSS feed for your Inbox. The feed URL that you would need to use is http://mail.google.com/mail/feed/atom, but your feed reader will need to support authentication for it to work. For example, Google Reader will not work when subscribing to that feed because it doesn’t let you input your username and password. I believe most desktop clients support this (I know FeedDemon does), and some online ones do as well (Netvibes does).
One thing that I didn’t know, and I have Google OS to thank, was that you can also subscribe to a feed for any Gmail label that you’ve created. All you have to do is throw the label name onto the end of the feed URL like this:
Tip: I’ve noticed that you should replace spaces with hypens in label names. Or you can just leave the space in the URL, but don’t try to delete the space because it won’t work.
All you have to do is replace LABELNAME with the name of the label you want to subscribe to. This is useful for me because I have one particular label that reports on the status of my backups that are performed every night. I have these skip the Inbox by default because I don’t want to wake up to fifteen different notifications sitting in my Inbox every morning, but now I can subscribe to a feed so that I don’t forget to check whether everything went through okay.