1. First, you need to install the GreaseMonkey firefox add-on https://addons.mozilla.org/en-US/firefox/addon/748
2. Next, install the required script http://userscripts.org/scripts/source/9540.user.js
3. Once finished, head for Google.
4. Double clicks the Google Logo and a box will appear similar to the figure below.
5. Now, you can type your own text ( letters and space ) and assign different color for each letter.
6. In color edit box, type the numbers: 1 – blue, 2 – red, 3 – yellow, 4 – green or other – random.
7. Click the “Change” button when finished and you will noticed the new Google Logo Text. :D