Arrrgh... my brain... it hurts.
Click this link to play "Triangles".
If that's a bit too much crazy in a small space, try this one: Shuffle. So far I've made it through three games before losing by one round. If you really like it then you can save the .swf file to play it offline. If you have questions about how to play a .swf file on your computer, ask and I'll answer.
*Disclaimer: Actual length of a week may vary, depending on if I remember to find something for the following week. In extreme cases of forgetfulness a week could last as much as a year.