Fritizing is a great tool when it comes to designing a circuit or a pcb. There are so many parts/boards in fritzing library. I feel the only big feature missing is Board Emulator & Circuit Simulator. This will help building & testing easy to complex prototypes on fritzing before trying with actual boards. I wish and plan to make such a tool and integrate with fritzing platform.
Please share your thoughts on this. If someone is interested to collaborate and develop this feature, then let's do it!