The bar on top of this website that says feature bar Its colored yellow and the text is green. I just don't know what it's called
They've simply made a div called #topbar. They've set the ad inside. This page is crawling with so much Javascript... ew. They've commented a lot out in what looks like the proper manner, but it shouldn't be sitting in the html in the first place. The fact that the bar is one of the last things to load on the page doesn't mean that it's put there by Javascript, (*Edit, it's Javascript all right) but I wouldn't be surprised (people use Javascript to do things normal html and css do easily). I'm surprised I didn't see the old MM_swap thing in there too. They've also compressed their html so it's damn hard to read. I don't know if it's ajax (meaning it would be working with XML), but most of the Js seems to just load stuff (tag cloud, login bar, etc.)... the login may be Ajax as just parts of that bar need to change depending on whether the visitor logged in correctly or not. That's certainly talking to the server and only reloading that little bit of info, but you can do with with Perl or anything else too.