I've been thinking about how to organize tags on gnolia.com, mostly I want something more hierarchical in nature then just top-level tagging. It doesn't really need to be built into gnolia, just something convenient.
There are two schema that I am thinking about, utilizing a file path style: e.g. programming/c++/qt or the namespace syntax my wiki software uses at home: e.g. programming:c++:qt. Then again, there's always programming.c++.qt and all sorts of other combinations. Really, I think I like the Java/Python style dotted namespacing or simple folder paths. The issues of dealing with separators that may be utilized within a tag name is always a factor to consider though#—but shouldn't be a problemo for me. Why do I feel like reading a book on database normalisation? One nice perk, i could always design a little bookmark mangaging gizmo as an external application or an AJAX page. Gnolia seems to have moved developer documentation into the wiki, so it shouldn't be to hard. I could cook up something client side fairly trivially, but doing it as a web app might be more 'fun' in the short term, mmm!!! Short of writing my own program, there's really no way for the UI to bundle tags within tags, that I'm aware of. (e.g. tag "Google" points to tags "Google/Services", "Google/Software", bookmarks for account "Preferences", blah blah). A simple tags cloud sorted A-Z however, makes it fairly easy to see that kind of relationship though.
I may also play both decks at once, and try managing my data with delicious at the same time; with a review to be made after a month or two. And of course, I can always whip up my own booksmark gizmo and place the server on Vectra for safe keeping.