sparklines
This infostetics article pointed me to sparkline.org. Sparklines are “intense, simple, wordlike graphics”, invented(?) by Edward Tufte. You can download a gd sparkline-library at sparkline.org.
My first sparkline (no use of that library though) is to the right showing the unique visitors on top and the spiders/bots on the bottom, clearly showing the spider/bot harrassment of the past two months. Since I don’t have privilige to do cron jobs I faked it: on every spider or bot acces to my site it checks the age of the sparkline image, if the image is too old it is recreated. I haven’t really tested yet how long before a time out (creating multiple or more complex images).
