As a full time web designer, there are a lot of free online tools that I use regularly. I have decided to categorise some of these and link to the most useful tools that you can add to your arsenal. Hopefully these will allow you to save time and become more productive in your web design.
CSS
Procssor
I write CSS in a multi-line format, with lots of white space and comments. That is great for a human-readable environment. But on a production ready website it is unnecessary. A best practice is to pre-compress your CSS before using G-ZIP to compress it even further when delivering it to the end-user of your websites. Procssor allows you to compress your CSS with some configurable steps.
Remember to keep an uncompressed copy of your CSS file for your own future use!
Layer Styles
I feel this is one of the best tools on my list. This allows you to create CSS3 effects in real time with a Photoshop like GUI. It then provides you the final CSS code that you can copy/paste directly into your own CSS files. It is really fantastic, and great time saver. Adobe need to pay attention to Layer Styles. Photoshop desperately needs a tool like this built in.