Twitter has this nasty habit — if you come across a tweet in your feed reader containing a URL, and you want to follow that link, you can’t, because Twitter doesn’t auto-link URLs in its RSS feeds. Instead, you have to click on the feed item, itself, wait for that to open in the browser, then click on the link in the new browser tab. That link will, in turn, open in another new tab.
Here’s a quick-hack Greasemonkey user script to inhibit this second new-tab: