In my old band, we had a song that was kind of power-poppy, then a really short solo, then I would pound the low E, drop it down to D while it was ringing/feeding back, then there was a chugging kind of riff on the rest of the song. Sure I could have played it all in standard tuning, but the WEEEEEOOOOOWNNNNN effect of dropping that string down was just too cool to pass up. It's not like I do it all the time or anything, but, yeah, I did it.