Charlie Hunter plays 8-string guitars made by the Novax company. The tuning is actually normal: E-A-D for the 3 bass strings (just like the bottom 3 on a normal bass) and the top 5 are A-D-G-B-E (just like the top 5 on a normal guitar). On his first album, before he got the custom Novax guitars, he used a seven-string to similar effect; his bass is not as strong on that album as on later releases.
He uses a Hughes & Kettner Tube Rotosphere pedal to get his signature organ-like sound, and often uses a tremolo effect on his songs. His amps vary depending where he's playing (he usually just rents).
It's defined as "jazz," but Hunter has covered a lot of ground; recording jazzy covers of Nirvana's Come As You Are and playing with former Primus bassist Les Claypool are not quite what your dad's jazz guitarist would do.
His latest album (Right Now Move - 2003) features Charlie Hunter in a quintet with trombone, saxophone, chromatic harmonica and drums.
Past albums included Charlie Hunter Trio (1993) and Bing, Bing, Bing! (1995) with a drummer & sax; Ready... Set... Shango! (1996) with drummer and alto and tenor sax; Natty Dread (1997), a cover of the album of the same name by Bob Marley; Return of the Candyman (1998) with Pound for Pound, a backing band of a drummer, synthesizers, and vibraphonist; Duo (1999) with just him and percussionist Leon Parker, his eponymous album (2000) with percussionist and occasional trombone and sax; and Songs From The Analog Playground (2001) which featured vocalists ranging from Mos Def to multiple-Grammy winner Norah Jones.
If you get a chance to see him live, take it. Despite a slightly disconcerting underbite, the man is a joy to watch and anyone who appreciates virtuosity ought not to miss him.