There are a few dedicated tools to search for del.icio.us tags:
allinurl: library site:del.icio.us
(only finds users who use the library tag…doesn’t show you a list of bookmarks…doesn’t work with some syntax like the underscore eg. LIS_km).
(results show a list of bookmarks with the specific tag)
Try the same search but also with the term ISBN appearing in the extended field or title field…here it is: site:del.icio.us subject:library isbn
Try multiple categories: site:del.icio.us subject:(library blogs rss)
Or you can do a plain old site search: site:del.icio.us library
(looks for the term “library” appearing in any of the del.icio.us fields - description, extended, title, url[?])
Search for a user, eg. site:del.icio.us author:johnt
(only 6 hits, hmmm…)
Found it unsual that a simple site search failed, eg. site:del.icio.us (without a search term).
Alternatively, this is the blogID for del.icio.us : blogID:27622
(not sure if this is meant to be similar to viewing the del.icio.us homepage).
I don’t think Blogdigger can handle syntax like, underscores, either.