felipehuggler.com

This is very nice. You can personalized console.logmessage styles google chrome.

How?

console.log('%cBlue!.', 'color: blue;');

The propertie %c receive style.

Or in Windows XP 

C:\Documents and Settings\<User Name>\Local Settings\Application Data\Google\Chrome\User Data\Default\User StyleSheets\Custom.css

.console-error-level .console-message-text{
    color: red;
}

.console-warning-level .console-message-text {
    color: orange;
}

.console-log-level .console-message-text {
    color:green;
}