In the old web days, a spike of new traffic to your website was normally just that, a spike. After the initial interest had died down the general traffic averages would return pretty much to normal.
An interesting characteristic of RSS is that the traffic is sticky. Once someone discovers your site is interesting and subscribes to your feed, they effectively never leave. This results in a constant upward trend for your traffic statistics.
I wonder what interesting statistics or views we could get of RSS data from the web server? For example, average number of requests / IP address / day; % of requests that returned 304 Not Modified; graph of the length of time it takes for a feed update to reach a majority or readers; subscribers gained in the last month; subscribers lost in the last month; etc.
Note: Originally posted to my Synop blog on July 22, 2004 and picked up by Scoble.