For a developer, staying up-to-date is a very important thing. New technologies are continuously emerging and though it is not considered necessary to use the last one, it's a good thing to know what is happening.
We would like to make some recommendations, in the hope that they will help you:
Dzone is a great place to check for programming news, tutorials, and a lot of resources. It is good to take a look at it almost everyday. Check out this link: http://www.dzone.com/links/index.html
You must have heard about Firebug—a Firefox extension that helps us debug the code—especially useful when working with AJAX. If you haven't heard about it, now is the perfect time to download it from https://addons.mozilla.org/en-US/firefox/addon/1843.
This is another Firefox extension I couldn't live without. This one helps you hover with your mouse pointer through any document, telling you the CSS classes of the elements hovered upon. As always...