The best charting site on the web. Easy to use and navigate your chart. Custom display features and nearly every indicator you can think of. There is also a very thorough stock screener and countless tutorials and trader education materials.
A one stop shop. The homepage may have more information on it than any other page on the web. Finviz offers excellent and excellent screener, super fast news feed and charts come with basic technical analysis drawings. Premarket info is also available.
My favorite screener on the web. The Chartmill stock screener has some of the most advanced technical screening that I have ever seen. They also offer preset screens under their "Trade Ideas" tab and great charts with technical and trend analysis.