One of the first things you'll notice about tiinker is that you don't have to create an account to try it out. Tiinker will remember you for a while using a browser cookie. You can click "try it now" from the home page to start rating stories up or down without ever having to log in. If you like the service, though, you'll want to create an account to save those rankings.

The interface itself is slick, fast, and easy to use. By default, tiinker aggregates content from thousands of news sources and blogs and sorts them into the categories of arts & entertainment, business, health & lifestyle, opinion, politics, science, sports, technology, and world. The stories are selected for you completely automatically, no humans involved. This is the key difference between tiinker and the other social news aggregators out there. With tiinker, story selection is all about you and what you are into - you can't even cross-reference your selections with others like you or your friends. This is a personalized news service, not a social network.

The news stories are chosen for you based on a complex mix of analysis of what they're about, how much you're interested in similar topics, how long ago they were published, where in the world they come from, and other factors. Tiinker will also sometimes present what they call "lucky dip" stories which are chosen to broaden the range of news you see, by exploring new topics outside of your common interests.

Ranking stories is as easy as clicking on the "thumbs up" or "thumbs down" and will help train tiinker to learn your preferences. You'll see stories becoming relevant to you after you've rated only a few articles, but it may take a few more visits for tiinker to really know what you like. The algorithm is continually learning as you use it and will get better at choosing interesting stories over time.

When you "thumbs down" an item, the service eliminates those kinds of stories from your profile right away. You also won't see stories appear from categories you don't browse. However, if you make a mistake and accidentally rank a story incorrectly, a useful feature allows you to click the thumbs icon again to undo your selection.

Another unique option is the ability for service to email you stories if desired. Upon signup, you can select to have tiinker email you stories daily, weekly, or never. You can also change this option in your settings at any time. There's an RSS feed available for your stories, and if you are interested in what the masses are reading, you can check out the "Popular" page, which has a feed as well. If you want to narrow it down further, each category page has a personalized feed and a popular feed, too.

If you start running out of things to read, you can click the "only unseen stories" link to see all the stories that have never been displayed for you. You might surprise yourself and find something of interest here.

To mark stories and save them for later by, you click the book icon underneath the item, which will save it to your "Scrapbook," a section of the site that holds saved stories. Of course, there's a feed for this as well.

Tiinker looks like a great service to help you sort through the massive amount of news published daily and gives you a more personal alternative to sites like Digg.  However, advanced RSS users will probably still want to use their feed readers in order to maintain control over their news sources, perhaps only using tiinker feeds to supplement their current RSS list. Still, the service is a big step forward in the capabilities of machine learning and for that alone, it's worth a look.