Yahoo! announced yesterday the new Yahoo! User Interface Library and Yahoo! Design Patterns Library, a very interesting AJAX implementation to make better Web 2.0 applications. With the UI and Design Patterns Library you'll be able to implement all the AJAX features that we have already met in Yahoo such the new webmail, drag and drops, tabs, rating ... and much more.

Everyone talks about Web 2.0. Talk is cheap. How about some real help? Just in time for Valentine's day we're giving you a delicious candy box of tools and guidelines for building cutting-edge dynamic web sites.

First, there's the Yahoo! User Interface Library. The UI Library is a set of JavaScript components that let you quickly add all kinds of really nifty features to your web site, from dynamic UI elements like drag and drop, tree views, and animation; to underlying functionality like custom events and easy-to-use cross-browser XMLHttpRequest connections. Its a small easy-to-use framework for building AJAX applications. And get this: Its free to use and its open source (BSD license). Better than flowers any day.

Code is cool, but howabout some advice, too. We've also got the Yahoo! Design Patterns Library, where our best visual and interaction designers have gotten together and created a set of patterns and guidelines for design in a Web 2.0 world. Here you'll find ideas on the best ways to implement web site elements, along with pointers to examples and the tools within the Yahoo! UI Library that will let you do it. Today's Pattern Library is just the beginning -- expect this part of the site to grow quite a lot over the coming months.