I propose trees as a topic, preferably to be used during the week leading up to or following TU Bishvat (which happens to be this coming Wednesday).
There are currently 12 questions in the trees tag.
What is it?
There's a single topic that people think about during the week and come up with good questions on. The topic is set each Wednesday or so.
What do I win?
An Internet with more good questions and answers on an interesting topic.