Audio is a big one. The HTML5 audio APIs just haven't caught up yet. Live video, as mentioned elsewhere, is big as well. The vast majority of web games are stil

Audio is a big one. The HTML5 audio APIs just haven't caught up yet. Live video, as mentioned elsewhere, is big as well. The vast majority of web games are still Flash, as well. Even video delivery is more robust with flash than with HTML5 - ever tried doing a preroll on an HTML5 <video> tag? Notice that it basically...doesn't work? Flash is certainly has less of a monopoly on "interactive web content" than it once did, but it still fills an extremely important and currently unreplacable role on the web. To be ringing its death toll just yet is premature.