Greasemonkey is a Firefox extension allowing for the customization of certain web pages to enhance their look and function. Tons of pre-canned scripts are available and easily installed into Greasemonkey to quickly transform sites with little or no user configuration. One such script called Photostream Graphr adds a little graph to the top of your Flickr home page to show you cumulative daily, up to the minute photo stream views. Over the course of a month you will see the daily trend develop in a graphed form. Mine can be seen as a squiggly pink line with a blue dot and the number 91 in the top right of the photo below...
Since I've just installed the Photostream Graphr on a new machine it's just starting to collect data but over time I should see trends on more of a monthly level. For an example of a Photostream Graphr with more data check out the post on Flickr here. I think the graph image has been updated in the most recent version but you should get the idea.
Links to the above mentioned software:
my Flickr pictures