I made a small extension for Opera browser, to advertise randomly selected goods on fler.cz website. They call it "to top" the item, and it means, that the product is listed on the top of the website homepage. Top action is limited to once per some time, given that time is based on the seller reputation score.
Extension uses browser's session, so the user signs in with the "remeber me" option checked and all is set. It waits for next topping time automatically and performs the top when possible. It disaplys the actual state of the extension in form of icon on the main bar of the browser.