I'm still persevering with delicious.com, which went downhill after the AVOS buyout but has improved considerably since then.

It's still not up to the standards that were acheived under Yahoo!'s ownership but I haven't yet found an alternative that gives me: a great Firefox extension, networks, good tag suggestions and an API.

Pinboard, Diiigo and Evernote are good but they don't fit with my workflow.