2 player scenario

http://www.fortunecity.com/boozers/brewerytap/1/IntSett.html

just for fun DONT TRY IT

http://www.virtual-cafe.com/~tdewey/diesiedler.html#Psycho

a very large one

http://www.geocities.com/captainqwyx/tctp.html

Indians on Catan

http://www.universityofcatan.com/scenarios/soc-vf01.html

Some translations from Das Buch (The book)

http://spotlightongames.com/rules/kolonien.html

Not up to date but nice to read, with different scenarios

http://txe.swa.com/games/catan.htm

In Poland they have the PC-game only

http://catan.topware.pl/