Just found a cool little utility that allows you to design tiling Escher-like patterns, the Real2Virtual Tile Designer.
However, the program seems a little dated and the user interface is atrocious. I was wondering if any of you knew of any other similar programs out there?
Hi Skaven
May this link interest you 
Big page :ex:
Particulary section 30
Pilou
Ps this one is funny : Drawing online in direct !
Have happyTesselatteing
Hundred other Activity on the same site !
Coolness! When I was Googling for the Real2Virtual Tile Designer, I also ran into a myriad of links with information about tiling and tesselation. And all I was looking for was a simple utility for creating cool tiling patterns.
Here’s another one: Tesselmania. It also allows drawing individual shapes onto existing tiles. I haven’t tried it myself, so I don’t know whether it is pixel or vector based.
Hi Skaven
Your link was in the “Big Page” above 
Pilou
Oh. Well, sorry I didn’t immediately read the whole page in its entirety. 
That is really cool 
David