Favicons are the small 16×16 pixel icons used to add an extra level of branding or customisation to a website. Any site can have a favicon added to it at any time, using a couple of lines of code.
The key to webcomic site design is keeping it simple and keeping it from getting ugly. “Duh!” you might say, but the internet is full of Really Ugly Sites and, unfortunately, that includes some webcomics.
Many popular comic websites contain little extra jokes in the form of mouseover text; the little captions that appear when you rest the mouse on a link, image or even general text. xkcd is probably the most famous for this, given that it has at least one joke or comment on each comic (and sometimes they are funnier than anything in the main comic).