The Plugin Site

seamless pattern type stuff
http://www.geocities.com/murakuma/plugins.html

magnify and equalize
http://reindeergraphics.com/free.shtml

gravitational lensing -- and an interesting lesson in optics
http://leo.astronomy.cz/grlens/grl0.html

Thanks for the URLs, but these and many others can already be found at

http://thepluginsite.com/resources/

o
thanks