Online resources for engineers

I am building a web page that directs visitors to various design tools available online. The website is primarily focused on power electronics, but I would be interested in hearing your suggestions on which online resources you feel are useful to electronics engineers in general.

Ex: Simulation tools, schematic drawing tools, circuit analyzers, parts/datasheets databases, etc.

I am not an electronics engineer myself, so I look forward to hearing the suggestions of women and men active in the field. Thanks to all in advance.

P.S. The EE-Web toolbox is already on my list

Scheme-it is an online schematic and diagramming tool that allows you to create and share technical drawings using your web browser. The tool includes a full set of schematic symbols for building electrical circuits as well as an integrated Digi-Key catalog that supports the insertion of product images and product photos into your drawings.

The tool also includes an integrated bill of materials (BOM) manager that allows you to associate each generic symbol with a Digi-Key part number.

URL: www.digikey.com/schemeit

PartSim is a free and easy to use circuit simulator that runs in your web browser. It includes a full SPICE simulation engine, web-based schematic capture tool, and a graphical waveform viewer. It also includes an integrated Bill-Of-Materials manager that lets you assign Digi-Key Part Numbers to your models.

URL: www.partsim.com

PCBWeb is a free browser-based CAD application for designing and manufacturing electronics hardware. It can design multi-sheet schematics with the fast and easy-to-use wiring tool. It can route multi-layer boards with support for copper pours and design rule checking. It also has complete integration with Digi-Key catalog and bill of materials manager.

URL: www.pcbweb.com

Digi-Key Corporation is one of the fastest growing distributors of electronic components in the world. Digi-Key is an authorized distributor of electronic components for more than 600 industry-leading suppliers.

URL: www.digikey.com

Franklin,
Err.... can you think of any others?

Check this blog site on a list of the different circuit design and simulation tools

URL: http://www.eevblog.com/forum/eda/pcbeda-software-list/

Great! Thanks for the suggestions.