Jon Udell has a screencast about the del.icio.us social bookmarking service, discussing how to choose just the right tag (by exploring what others are doing and also keeping track of your own tagging).
There has also been some good discussion on the del.icio.us mailing list about tagging as a collective vs. individual activity. Do you tag for yourself or for the community?
When I started my del.icio.us account, I tagged with every possible tag that would fit. As I saw my list of tags grow and got tired of scrolling up and down for tags with only a single entry, I began tagging conservatively. Then, I started thinking of the community and added tags that I thought would fit the bookmark topic well and make it easier for others to find the entry.
delicious udell socialsoftware