One of the best is a “social bookmarking” site called del.icio.us, recently purchased by the search engine company, Yahoo. It adds a new and powerful dimension to the concept of the browser bookmark, turning it from a purely personal and local tool, via the power of the network, into a distributed cataloguing system. As individuals around the world bookmark articles they find on the Web and attach a classification, or “tag”. The del.icio.us software aggregates the results.

At Bleeding Edge, we use it in a couple of different ways. First, it’s a way of staying in touch with the things that other people find interesting, serving, if you like, as a fuzzy search engine. One of the first things we do when we boot up the computer every day, is head for the “popular” page, and browse through the offerings. While we’re at it, we’ll often check out the most popular tags on the right of that page. We rarely come away empty handed.

But that’s not its major purpose. Once you set up your own account, you can use it as your own bookmark storage. If you’re away from your own PC, all you have to do is log into your del.icio.us account, and they’re instantly available.

You start by registering, preferably with a login you’ll find it easy to remember. Once you’ve got your account, you can log in, and select how you’ll add bookmarks. You can select a button for your choice of browser, or if you’ve got Firefox, take advantage of an official extension at which tightly integrates del.icio.us into the browser. That’s the one we’ve chosen.

Once you’ve got that running, the next time you find something you want to bookmark and tag, you click on your button, and it will trigger a page with the URL and description already filled in, and some suggested tags.

You’ll find a useful beginner’s guide which will introduce you to some neat little tricks. There’s some additional tools here.

The ability to search on any tag makes del.icio.us a powerful research tool. If, for instance, you’re interested in viral marketing, you could go here.

We did that exercise a week or so ago, and quickly came up with some interesting articles that we hadn’t found in a fast search of Google.

If you’re interested in digital images, you’ll find another Yahoo acquisition, Flickr, equally rewarding as a tool for searching for and labelling images.

You can upload and tag your own photos with a free, bandwidth-limited account, or a paid account. But perhaps Flickr’s most compelling features relate to its community. You can comment on other people’s images, and learn a lot from the comments of others. There’s an FAQ here.

In our opinion, searching for images at Flickr yields consistently better results than Google Image.

There’s some handy hints for Mac users too.

We wouldn’t be surprised if Yahoo buys another site that we’ve found useful for keeping up to date with news: digg.com

It rates stories on the votes of readers – a development which probably won’t be welcomed by editors, who are paid for their ability to pick what readers want.

A similar service is Memeorandum, which includes a section dedicated to technology stories.

Tools like these make a real difference.