Del.icio.us

Syntax	Title	Language	Target URL
du {user}	delicious: user bookmarks	All	http://delicious.com/{%user}

du {user}, {tag}	delicious: user bookmarks with tag	All	http://delicious.com/{%user}/{%tag}

dt {tag}	delicious: tag search	All	http://delicious.com/tag/{%tag}

dp {tag}	delicious: popular	All	http://delicious.com/popular/{%tag}

ds {query}	delicious: search	All	http://delicious.com/search?p={%query}

dadd {url}	delicious: add URL	All	http://delicious.com/post?url={%url}

dc {url}	delicious: check URL	All	http://delicious.com/url/check?url={%url}

[edit] Examples

du bob: Del.icio.us bookmarks of user bob
du bob, language: Del.icio.us bookmarks of user bob tagged with language
dt berlin: Del.icio.us bookmarks tagged with berlin
dt berlin+map: Del.icio.us bookmarks tagged with berlin and map
dp berlin: Del.icio.us popular bookmarks tagged withberlin
ds berlin: Del.icio.us search for berlin
dadd http://www.google.com/: Add http://www.google.com/ to your bookmarks (you must be logged in)
dc http://www.google.com/: check who bookmarked http://www.google.com/