Broad thoughts on tags for blog entries
Yes, I know, tags are on my mind lately. In particular I've been thinking about what I want to do with them. Ultimately what it comes down to is supporting real blog usability, specifically both encouraging and rewarding blog visitors for exploring outwards from whatever entry they initially landed on. When I wrote that entry I said that the most powerful way to do that was probably some sort of 'related entries' feature; tags are an obvious way of providing that.
There is an important corollary: for this to work, the tags must not merely lead to related entries but they must be related in a way that your visitors are interested in. Some tags will be too general to be useful (these are really broad categories) while others will be too uninteresting or obscure. This means that creating useful tags requires thinking about the relationships that visitors will want to explore; in other words, what about any particular entry that people will want to read more of.
(This is one reason that I think tags will be somewhat retrospective; you won't necessarily realize those interesting relationships until you have another entry to relate the first entry to.)
Also, tags aren't enough by themselves because they are too unspecific. There are at least three sorts of more specific relationships that I think will get lost in a general tag cloud and should be handled differently by at least the blog's UI: 'related entries', the more specific form of related entries that is 'entries in a series', and 'this entry is updated by ...'. Related entries is more specific than merely sharing tags; one way I can look at it is entries that share a topic even if they aren't specifically a series. Entries that are one entry in a series should have strong support in the UI for real blog usability because these are the entries that a visitor is most likely to want to read more of if they liked their initial entry.
(So in UI priority it should be 'this entry is updated by ...', 'entries in series', 'related entries', and then general tags, based on what I expect visitors to be most interested in and what's most important.)
In thinking about this I've wound up with the feeling that tags are going to work quite well for certain sorts of entry to entry relationships but not necessarily very well for others. Probably I won't fully understand this until (and if) I implement some sort of tags and other relationships in DWiki and start using them.
(As a result, any scheme I set up in DWiki should be flexible about what sorts of relationships it can associate with an entry or a bunch of entries. I will probably want to use it for more than tags.)