Hitwise has released some statistics on the popularity of various web based feed readers.

The market share of US visits to Bloglines was 3 times greater than Rojo, its nearest competitive web-based feed reader. The chart below shows the traffic trend over the past year for the leading web-based feed readers. You can see that Google Reader has grown lately, but as of the week ending 1/13/07, it had only 1/13 of the market share of visits of Bloglines.

I can understand the growth of Google Reader and hazard a guess that it is even underestimated, and that there is likely a large pool of My Yahoo users as well.

RSS is still a niche activity, when considered in whole, and the leading blogs, based on traffic & RSS stats, are still by far being visited mostly on site.