Seems like I'm not the only one that can't get access on-demand. For the curious, here is what the site looks like: http://cl.ly/image/0a3V1d2W1c3J (Each group of three lines in the top bar graph represents one day.) It also lets you know if your tweet attains an unusually high "reach" is: http://cl.ly/image/1p2X3b0x2X1S - which corresponds to the number of feeds your tweet showed up on via retweets.