Update: Diigolet (Diigo Bookmarklet) is currently broken. If you want to restore it please vote to resolve the bug or advise on Twitter
From the Delicious support forum (the page is no more available):
Q: 95% of the time I tag my bookmarks will all the recommended tags and add a few of my own. It would be wonderful if I had one button available that would select all recommended tags so I can get on with adding my own and and deselecting the recommended tags I disagree with.
A: We generally think it’s helpful for people to be selective when adding tags to their bookmarks, and ‘select all’ could encourage people to tag bookmarks with minimal thoughtfulness (which is less useful in the long run).
Tagging is the most effective way to organize bookmarks and to retrieve the right one(s) later by browsing or by searching. On the other hand, it requires some mental efforts to build and follow a classification scheme. This is why I became interested in bookmark managers offering some sort of automatic tagging feature. To this respect, all the ones I know (Diigo, Delicious, Faviki) are far from perfect. Nevertheless, I disagree with the argument of the reply cited at the top of the page. I am a lazy user. I don’t want to be bothered with thinking and writing all the relevant tags about the subject of the page I’m bookmarking. I want an automatic system that makes it for me, even if its tags are not always meaningful. My claim is that the duty to provide a better and better service comes before the need to manually correct its shortcomings.
Diigo has became my preferred boomark manager even because its bookmarklet allows to click a link to select all the recommended tags at once. Indeed, as a very demanding person, I would have liked to see all the recommended tags selected by default. Similarly, Diigo bookmarking window offers some other options (private, unread, cache and twittered bookmark) which are turned off by default, while almost all the times I would have liked to see some of them automatically enabled. This would makes me able to save a bookmark with a single click.
The bookmarklet turn on all the options by default. If you want to modify such settings, you have to edit the url property and modify the five-digits string assigned to the DG_NewDef variable. Each char is equal to zero or one depending if the corresponding option will be set off or on. The five options are: Private; Unread; Cache; Twitter This; Recommend all tags. The following 1-minute video shows how to use the bookmarklet and change it according to your preferences.