Some of the following may be of interest to non-subscribers, too:
In the good old days, before Blogger made labels available, I posted hundreds of unclassified items. Now whenever I introduce a new label, I apply it to as many old posts as appropriate, in order to include the old material in the label scheme, along with the newer stuff. FeedBurner doesn't understand me well enough to know that this is what I am doing, and whenever I put a new label on an old post, it tags that post as newly-published and sends out a link to it in the daily feed. So this is why you are seeing links to old articles as well as new ones, not every day but sometimes.
I would hope you would find these old links helpful in providing more background, and if they're not extremely helpful then I hope they're not extremely annoying. You can take some comfort in the thought that someday, eventually, I will have all the labels in place that I need, and I'll be able to stop adding new labels to old posts.
For non-subscribers who find this blog interesting, you may wish to consider subscribing. It's free and easy (just type your email address in the form near the top of the sidebar and click the button below it), and you'll receive one email per day with the headlines and a few words from each of the current stories. I subscribe to it myself (otherwise I wouldn't know what it looks like to the other subscribers) and I'm impressed with how good a job FeedBurner does with it.
In other words, when there are errors in the daily feed they are mine alone.
If you have a blog of your own and you don't use FeedBurner, you might consider checking it out. It's a nice package of services, it comes with no hassle, and it's free. Click here for more information.