I added a "dubious" tag to something on Wikipedia. It was fun and satisfying and I recommend it if you can find a sufficiently unlikely allegation. I'm awarding myself bonus geek points because the fact in question is whether the commonly accepted date of a particular event is correct in the Gregorian or Julian calendar. The page currently claims Julian, but my preliminary research suggests otherwise.
Be the first to guess the date I'm referring to and you'll win a prize. Be the first to authoritatively resolve the dispute and you'll win a much cooler prize.
Blu-Ray beat HD-DVD, and the high-res DVD format was is over. I pity the fools who bought HD-DVD players, which are basically worthless now. They're like those people at the race track who find themselves holding a fist full of worthless paper at the end of the race. (At least, that's what they do in movies.)
Format wars are nothing new though. The battle over the color television protocol is an odd one. In 1950, the FCC ruled in favor of CBS' proposal (because their demo worked well), but in 1953 was forced to reverse its decision because RCA kicked their ass in the marketplace. RCA's proposal evolved into NTSC, and all 100 CBS-compatible color TVs were scrap.
The AC/DC war in the 1880s was even more colorful. AC power eventually triumphed, but DC had a large user base in New York City. Most buildings converted to AC or installed local transformers, but the local electric company (Con Edison) was still delivering DC power to a few customers until a few months ago.