In rock and blues, it's not too uncommon to find bass players tuned to Eb because ther are lots of guitar players who do it. Guys like Jimi Hendrix, Stevie Ray Vaughan, and Eddie VanHalen are well known for using Eb tuning. Consequently, their bass players have also tuned down to accomodate them. I tune my guitars a half step down, but keep my 5-string bass in standard tuning. For thos who want to go lower, there are several options available. One is the Hip-Shot bass X-Tender key. I've read that Otiel Burbridge, who is currently a member of the Allman Brothers Band plays a 5-string tuend E-A-D-G-C. With the X-Tender key he can drop the low E down to B which effecitvely gives him a 6-string bass. The key can be adsuted to detune from one half-step to a 5th below. Most comments that I've read about them are favorable and they do provide a workable soloution to having an extended range bass without haveing to adjust to playing a 5 (or more) string neck. Another alternative is to get a sub-contra bass. This is a 4-string, but it's tuned C# (below B), F#, B, E (open E). Now if that doesn't tod it for you, then you need some help. Yet another alternative is an octaver pedal. Calr Martin makes one designed specifically for bass and has excellent tracking qualities. The thing is that the pedal can not handle multiple notes or ghost notes. It would come in handy for playing smooth flowing sub-terranian lines, but if you're going to slap and do double stops and all that, then you wuld have to swith the pedal off. And while we're on the subject of tuning: why is a piccolo bass (tuned EADG - same pitch as a guitar's bottom 4 strings) considered a bass while a baritone guitar (tuned like a standard guitar, but one octave lower like a bass) is not?