I've been working on the overload RSS reader a bit the last few days, and put a brandnew snapshot online. It's a great deal faster [calculating of the number of unread items was a tad slow, taking 6 seconds for my 69 feeds and 17000 items total and 5000 unread, now 0.09 seconds]. And... it has XMLHttpRequest, which some of you may know as AJAX.
A very nice example of this technique is GMail, Google's mail service. All actions are [almost] instantly, because they happen in the background, and information is preloaded [hence the "Loading..." message when visiting]. I don't want to overdo it that way, but introducing it for some buttons happened to be working out very well.
Please take a look and give me some feedback! And yeah, I know the icons suck a little. Does anybody have ideas for better ones?