This depends a lot on your interpretation of "create," as well as "day."
As my answer to another question explains, some believe the seventh day has not yet ended. If you take this view, the answer to your question might be "no, God has not created anything since the seventh day, because nothing has happened since the seventh day." I think that probably misses the real point of your question, though... I think you're really asking, did creation end after the sixth day.
If you hold to the views of most old earth creationist, the substance of the universe was created instantaneously at the event of the Big Bang. Since then, God has created various life forms, humans being the last one mentioned on the sixth creation "day."
Clearly God has caused certain things (both physical, and non-physical things) to come into existence after the end of the sixth day. Many people have been born, new rivers have formed, the Church was created (a non-physical thing), etc. It's even possible/likely that micro-evolution has occurred (although there is debate whether the result can be considered new species or not). Would you consider that to be "creation?"
The view I would hold is that after the 6th day, God ceased to create new species of plants and animals.
However, this is hard to prove scientifically, because not enough time has passed since the end of the 6th day (possibly as much as 10,000 years, depending on your estimates). And according to geologists, the fossil record goes back hundreds of millions of years. There simply aren't enough data points in the last 10,000 years to prove that life isn't continuing to be "created."
So in a nutshell... without further clarification in your question, I think the answer is "It's impossible to say."