Sorry. Don't know of a site. Major seventh barre starting on 4th string (D string) is fretted for G Maj 7 starting from 4, 5777, therefore G7 (dominant) is 5767 and G6 would follow as 5757.
This most common 4th string barre has the root on 4 string and is the same fingerings as the standard open D chord (plain old G chord starting on 4th string in our above example would be 5787).
The easy way to figure where you need to be on the fretboard for the root of the chord is to realize that the 4th string is a major second lower than the octave E from the bass string E. So, if you need a G chord on the 4th string it will be 2 frets higher on the 4th string from where it would be for the G chord barre on string 6.
[B]"What people don't understand is... The World, indeed the Universe, depend upon, nay, hang upon, the downstroke of a Guitar Pick!!!"