Category based online bookmarking site

Hi all,
I hope I won't be frowned upon for posting this question here.

I want to find an online bookmarking site that has IE like organisation for book marks. i.e. category based. (It would be nice to have tags as a secondary thing).

Anybody in the know?

Try http://delicious.com/. It has tags (which also serve as categories) and a set of tags can be grouped into bundles.

Thanks. I'll check it out.
But I want sub categories too.

e.g. java -> generics
java -> regex

etc.
Any more pointers are welcome..

Tags are much better than category hierarchies. Just tag a bookmark with "Java" and "Generics".