Thanks for including CircuitLab! Our users are telling us that they're using our in-browser circuit simulator (https://www.circuitlab.com/) to replace desktop-based software such as Cadence PSpice, NI Multisim, and Linear's LTspice. All in all, our engineering, academic, and hobbyist users ran more than 100,000 circuit simulations using CircuitLab in the last week alone! Those two facts together are telling us great things about the future of browser-based applications.
Thanks for building it! I've been using it as a schematic editor for about the last 6 months to illustrate posts online (I haven't tried the simulator yet) and it's the most impressive software feat I've seen in a long time.