We were chatting about faster alternatives to
sin(x) in chat and invariably a few equations started cropping up. A few links to Wolfram Alpha plots (example) were pasted into the chat and I was a bit disappointed that we didn't see the graphs directly in the chat (like you see questions etc.). This would be a clear winner on at least 3 StackExchange websites (Math, SO and GD).
In addition it would be helpful to be able to use Wolfram Alpha results in questions and answers, for example if I was elaborating on the difference between O(n) and O(log(n)) I would be able to provide the graphs directly: very important for critical topics like premature optimization.