If you don't use del.icio.us yet, hop over, register a user and start storing your bookmarks (aka favorites) online. Besides having your bookmarks available to you from every computer that has internet access, it also enables you to browse the web in a whole new way - by finding users who bookmark similar content for example. (See which pages I have bookmarked at delicious by navigating to http://del.icio.us/DanyX/ )
Delicious lets you store a description and so called tags (=keywords) together with the bookmark. You can choose them freely, whatever makes sense to you. You can then view your links by tag (see my delicious links tagged with art for example) and you can also view which pages have been bookmarked with this tag by any delicious user. (here are all pages tagged with art)
What I find so interesting about this is that it lets you view the web from a totally new perspective. Up until now, I mostly used google plus a few news pages to browse the web, plus occasionaly wikipedia. Whenever I would stumble upon something interesting in real-life, I would google it. This would return those pages that google thinks are most relevant - which basically means that this page has the most pages linking to it. For certain things this works fine, e.g. if you are looking for the webpage of a huge company (when I enter IBM, Industiral buisiness machines is the first google hit and should be).
Using this technique means missing a lot of "hidden gems" tough. It also means, that you only find what you are activly looking for, or what you stumble upon by accident. Delicious on the other hand lets you find people who like the same things that you tought interesting - and then look at what they bookmarked. You get a link collection not of some dumb web-crawling spider-bot, but that of a true human beeing. Granted, quite a few or maybe many of her links will be of no interest for you, but if you found her by similar linked pages she is bound to have at least a tiny bit of common interest with you. And chances are good that there will be interesting pages at her delicious site as well.
I agreed with my friend fabian the other day that delicious of course is also a propaganda tool. By bookmarking something publicly, you implicitly say "This is important". And your tags provide a (obvious or hidden) valuation. Inhowfar this might be abused remains to be seen - for the time beeing I don't think any del.icio.us-bombing is happening or would be very worthwhile.
Another point I find remarkable about delicious is the picture you get of a person of whom you know nothing but his chosen nickname and bookmarks (which in turn is an interesting subset of his interests). Try it with some random people!
There is a lot more to find out about delicious and the potential of social software in general - it remains to be seen if it turns out to be just another hype or something as essential to us in a few years as google is today. The benefit of using it is available now however - so start using it and tell me your nick!