Circuit simulator. Virtual analog indeed.

[GuyaGuy]

This is kind of neat.

https://www.circuitlab.com/

It lets you build your own circuits and sketch and share schematics. Seems relatively basic but could be a cool learning tool for people who want to learn circuit design.

[garranimal]

I'll have to check this one out. Similar to LTspice, I've been scratching the surface.

[Projectile]

Wow. This is by far the most intuitive, easy to use spice tool I've ever used. It's still a bit too basic for serious analysis, but I wish every spice tool had a GUI this nice. I hope they keep developing it until its a really mature piece of software. I don't understand why every circuit simulator out there has to have the such a backwards, difficult to use interface. LTspice was a big step forward compared to Pspice, but this time someone finally got it right.

[dbagchi]

Very true. Circuitlab Rocks ! I came across one another cool one at http://www.DOCircuits.com. This one has real looking components and devices !

[MaxBlack]

It's a interesting tool and could be a option for free EDA tool users! I have played around with it ,but now I have been using EasyEDA for over a year,it's a excellent simulation product.EasyEDA also has good simulation support using ngspice. Many LTspice simulations can be run in ngspice with little editing effort.The tool allows you to import an old design from several other circuit maker tools, it has the ability to export the designs and simulation results in .PNG or .SVG formats, and can be a host for your partners and colleagues if they want to work on your projects.You really deserve a try at https://easyeda.com/.