It may be a little daunting for the beginner, but it is a very powerful program if you have a musical background. You can set the strings for any tuning, ask it to show you notes or intervals, find chords, show scales, modes, etc. Some of them are very arcane. Now if only it would display Hawaiian koholos...
I think Donley Smith mentioned this same site several years ago on TaroPatch, and I have been using it ever since then. It has moved around to different locations on the web in the meantime.
I especially like that it shows the fretboard
IN A HORIZONTAL LAYOUT !
which is the way I perceive the fretboard when I look at it. Whoever decided to display chord charts with a vertical layout, and how it became standard in chord books, I will never understand.
I use shift-printsceen to capture the fretboard image and then paste several of them together on a page with a photo edit tool. I just wish I could get better resolution that what is gotten off a screen capture.