I also just found a website that does challenges with zentangles. The website is called I am the Diva. They are currently on Challenge #34 so I am a bit behind. I will probably start with the next challenge and might catch up on the others slowly. If I continue doing them I will need to buy better pens.
And now I present to you my first zentangle...tada!
*Update - This is actually considered a Zentangle Inspired Art since its not on a 3.5 inch tile. So it doesn't really count for my 32 Things by 32. However the ones done the day after this do count. Click here for those.