Slashdot implemented a tagging system so that account holders can tag stories. After all, tagging is the latest (and thus coolest) thing ever! The problem is that people don't use the system correctly, to the extent that most tags are almost worthless. For instance, a recent story titled "Rumsfeld Stepping Down" is tagged thusly:
yay, finally, haha, itsatrap, politics
There are many other examples, but every time I see stories tagged simultaneously with "fud, notfud, lies, truth" I grind my teeth at the uselessness of it. This has driven me to consider again the value of tags, their potential for misuse, and how tagging applies to my photos.
I have a number of tags that I use to keep track of locations at which a photo was taken, such as "Columbus OH" and "Denton TX". There is nothing particularly wrong with these tags, except that I'm using them in place of more appropriate metadata: GPS coordinates. Just as I wouldn't want to tag my photos with "November 2006", I don't want to use tags to indicate the location at which a photo was snapped.
My model of camera doesn't have support for GPS, nor does my photo manager (yet). One day I'm certain I'll have that capability. Until then, I'll continue abusing tags for geographic metadata.