Pinboard is the successor to Delicious and various other social link repositories. It's a service I get a lot of use out of because some parts of following the news, monitoring various government / non-governmental sites etc means reading lots of small articles each day. If, in the future, I want to return to a particular article, I generally don't want to have to go through the hassle of searching for it afresh (sidebar: use DuckDuckGo instead of Google! It's great!) so I just click a button to save a page in Pinboard when I think there's a chance I'll find this useful or I want to preserve it in some way. (Visit the 'tour' part of the site to learn more about how Pinboard works.)
Pinboard also auto-adds links, if I've starred, retweeted or saved anything in Twitter. Also if I've added a link from twitter or elsewhere into my Instapaper (Pocket is also used by some people, and is supported by Pinboard), then these articles are also autosaved into Pinboard. I reason that if I've taken the trouble to save it for reading later, then there was probably something in there that I might find useful in the future, or something that I might want to reference later.
The great thing about searching your repository of pinboard links is that you can do in-text searches. So you're not just searching the name and URL of the link, but you're searching the full text of the page. This is really useful, especially if you have many links saved. I just checked my account stats and see that I have over 60,000 bookmarks saved in my pinboard account. This is over 15 years worth of bookmarking.
Pinboard also offers a paid upgrade service where it will archive copies of a page and store that archived image. That way, even if the site is later taken down, or someone deletes the page, or anything at all happens to the page, then you still have a copy of the page and can search in it, can download it etc. Needless to say, this is really useful for monitoring the Taliban's websites, for example, which are frequently targeted in take-down attempts and where data is periodically deleted from servers or changed in various ways. I often double down and make a manual archive copy of important messages/pages to be stored in DevonThink, but I generally rely on Pinboard to handle the bulk of this work for me.
The creator of Pinboard, Maciej Cegłowski, is a smart guy and who writes interesting things, and the service reflects this. (Check out his interview on the Longform podcast). It's a paid service, but is relatively inexpensive as far as these services go. Moreover, the paid nature of the service means that there's relatively little (if at all?) creep factor to using it. Pinboard isn't selling your link database on to anyone else, they aren't marketing data profiles of their users etc. It's a solid service.
The interface is pretty minimal, which I like, but in case it's not to your taste you can browse your links in any one of a dozen or so apps which can hook up into your Pinboard data. Links are fully taggable, including tag nesting etc, so you're fully covered on that front. There's a social element to pinboard that I don't use much (mainly because I don't know many others who use pinboard for saving links) but I can see that that might be a useful feature if you have a community working on a particular topic or area.
Pinboard is easy to use, reliable and relatively inexpensive. It can save you time and help you find things you read on the web. Check it out here.