Selfsimilarity on Stamps[size 1024x768, please] two applets
A first day cover dedicated to the Finnish Science Center.
On the stamp, partitioned in tangram pieces, look for the (approximant of) the Sierpínski Gasket,
a selfsimilar figure of Haussdorf dimension log(3)/log(2) = 1.5849.. found by Sierpínski in 1915
(the triangle in the center showing it also, is actually silvercolored; what you see are reflected colors originating from the scanning device)
Suomi Science Center First Day Cover

. I clearly remember Benoit Mandelbrot's inspiring talk at the IMC 1983 in Warsaw. It lasted at least half an hour beyond schedule, but no one left the overcrowded lectureroom, though dinner was waiting. For the references above (e.g. Cesàro) I consulted his innovative book on the fractal geometry of nature.
Two Koch curve applets by Albert Kluge
Valid HTML 4.01! Move your mouse pointer into the triangle and click the left button a few times [and then the right button etc.]

two more applets
Sierpinski gasket applet
idem, as an L-system

Here L stands for Aristid Lindenmayer (1925-1985),
a biologist from the University of Utrecht, my alma mater.

Some links to L-systmems sites:
introduction, by Gabro
tutorial, from Calgary
sketchbook-project by R.S.Ferrero
Trinity L-systems group
2-d L-systems, by R.M.Dickau [with Mathematica]
recursive structures, by M.Szell [in German]		 Koch's snowflake
a snowflake curve of Hausdorff dimension
log(4)/log(3) = 1.2618...
invented by Helge von Koch in 1904 and described in a Cantorset like fashion by Cesàro the next year.

a selfsimilar succulent
[from Sabinosa, el Hierro, 2005]