Recently i was informed about a new free online circuit simulator in the block - PartSim.
PartSim is a free, full-featured online circuit simulator that can be found at http://www.partsim.com/. It features a full SPICE simulation engine, web-based schematic capture tool, and graphical waveform viewer. It runs directly in your browser without the need for plugins and supports multipage schematics. You can see a full write-up/description here - http://www.partsim.com/blog/ready-set-simulate.
I tried it myself and found it really easy to begin with and run a simulation. In includes AC, DC and transient response analysis, as well as a BOM list. There is also a parts-list from Digi-Key to assign Digi-Key part numbers. Here is a short demo video: