Description from the page:
A free online Java program/applet/tool which allows you to explore, search and build hundreds of guitar chords. Easy to use, with colour-coded displays. Features include a chord database/dictionary, a voicing builder, a powerful chord search engine, and more. Dual display -- fretboard and chord structure (intervals). Use any string tuning. Build unusual custom chords.
I've come across many websites with guitar chord programs, but I've never been totally satisfied with any of them. Some have terribly complicated controls, some produce confusing chord diagrams, and some even contain incorrect chord voicings. I wanted to create a program that's both powerful and very easy to use, while still making it free for all to share. GCE is the result. I don't pretend to think that it's perfect, but it provides several features which I personally find very useful when writing or tabbing songs, and I hope that others find it useful too.