My answer to the TOD would be a fairly lengthy and interesting one...to myself, if no one else. I "discovered" eBay in early 1998 and was quite active buying things for the next several years. A whole variety of things. Too much stuff, probably, but I lived and learned. And I did come up with a few treasures along the way.
But you know what I remember most about it? The community. There was no Buy It Now at first, and they didn't disguise bidders' handles -- so you actually got a feel for who the major players were in your area of interest, and you could often make an educated guess how successful or unsuccessful you might be in winning a given item. And when new, you soon learned about waiting and sniping at the last minute. But there were no automated systems, so you had to do it manually -- and it was fun. There were items I'd set my alarm and get up at all hours for, and thus just a whole spirit of adventure about the whole thing.
Now of course there are still collectible and fascinating things to look for, but the game has changed -- for the better, in online improvements and convenience (remember mailing a check or going out to buy a money order??), and unfortunately for the worst in so many other aspects I couldn't even count them.