Geek Trivia: #Twitter #Hashtags

How are hastags started in Twitter? How do we decide what words to use? And is there an etiquette? I found these answers on the Twitter Fan Wiki:

• The hash symbol is a convention borrowed primarily from IRC channels, and later from Jaiku's channels. 
• It can be helpful to do a little research first, to find out if the subject you're tweeting already has an established hashtag., example, track other tweets on the subjects you're interested in browsing/searching atHashtags.org, TwitterGroups, TweetChat, TweetGrid, Twitterfall, or via RSS. 
• Hashtags were popularized during the San Diego forest fires in 2007 when Nate Ritter used the hashtag "#sandiegofire" to identify his updates related to the disaster. 
• The use of hashtags is still an emergent phenomena, and as such, etiquette is negotiable, though some have already expressed their distaste for hashtags. 
• Used excessively can cause annoyance, confusion or frustration, and may lead people to stop following you. It's best to use hashtags explicitly when they're going to add value, rather than on every word in an update.