I don't know how I survived long-distance travel before mp3s. You can only carry around so many cassettes or CDs. When I leave the house for a trip my earbuds are pretty much a permanent fixture until I am home again. At home, if I'm at my computer, I'm probably listening to something all the time. I listen to lots of different genres of music, but overall my standard, fall back is something within the electronic realm.
Last week I had a work trip up to Penn State University for a few days. It is so close (only three hours by car) that it made more sense for me to drive up than fly. I twiddled with the radio for a while before I finally gave up and popped in a CD. I ended up sticking in one that I haven't listened to for a while, which Colleen and I picked up after seeing the band live last year. We'd never heard of the opener for the band we went to see, Po' Girls. Hoots and Hellmouth not only warmed up the crowd but got everyone up on their feet and stomping along. They are an amazing live band. They dropped a board on the floor and stomped, clapped, danced, played and sang 'til the crowd couldn't help itself. The music is indie rock where you can feel the country/bluegrass/gospel roots right under your feet. The shows are tent revivals for rockers.
So, recently I have been stuck on Fluke. They may be most well known to the general population (if at all) for the "sex/rave scene" music in The Matrix Reloaded, a track called Zion. Unless you listen to stuff like Chemical Brothers, The Crystal Method and Underworld you probably haven't heard of them.
I am not into music to the same degree I used to be years ago but I do have a nice big 30GB mp3 player that has a full range of music on it that I use for the commute back and forth to the big city. Now, I occasionally I go to random mode or even genre but most of the time I scroll through, find an artist I want to listen to and pretty keep playing it until I get sick of it. That normally means I listen to one artist or album for at least 3 or 4 days and often a week or more. Over and over again, an hour each way, each day.