I almost always have music playing while I work ( a habit I picked up doing homework - as a way of drowning out the other kids having fun outside). I also have a ridiculously large collection, and I've always had ways for random selecting music to play. My first was little bits of paper in a candle holder with the initials of all 12 albums I owned, including: LZVF, WYWH, DSOTM, NATO, DATR, GBYBR, LITS, COB - that I would pick out randomly to see what to play next. Then I got to the stage of recording all my vinyl on cassette and I'd use the cassette counter to pick the next cassette (that lasted from cassette #105 (210 albums) up until cassette #1545 (3000+ albums). That lasted well into the CD era. But since I came to Cairns I've gone mp3 mad - and wonderfully WMP has shuffle.
As you can imagine, having 230,000+ songs on shuffle leads to some very odd juxtapositions. I just heard one of the more striking so it's inspired this thread.