Write to browser Javascript console from Silverlight in most browsers. Works with code outside of UI thread.

Log.cs

// Credit: Kodierer http://bit.ly/pqcSq

using System;
using System.Threading;
using System.Windows;
using System.Windows.Browser;
using System.Windows.Threading;

public class Log
{
	public static Write(object message, params object[] values)
	{
		HtmlWindow window = HtmlPage.Window;
		var isConsoleAvailable = (bool)window.Eval("typeof(console) != 'undefined' && typeof(console.log) != 'undefined'");
		if (isConsoleAvailable)
		{
			var createLogFunction = (bool)window.Eval("typeof(sllog) == 'undefined'");
			if (createLogFunction)
			{
				// Load the logging function into global scope:
				string logFunction = "function sllog(msg) { console.log(msg); }";
				string code = string.Format(@"if(window.execScript) {{ window.execScript('{0}'); }} else {{ eval.call(null, '{0}'); }}", logFunction);
				window.Eval(code);
			}

			// Prepare the message
			DateTime dateTime = DateTime.Now;
			string output = string.Format("{0} - {1}", dateTime.ToString("u"),  string.Format(message.ToString(), values));

			// Invoke the logging function:
			var logger = window.Eval("sllog") as ScriptObject;
			if (logger != null)
			{
				// Workaround: Cannot call InvokeSelf outside of UI thread, without dispatcher
				Dispatcher d = Deployment.Current.Dispatcher;
				if (!d.CheckAccess())
				{
					d.BeginInvoke((ThreadStart) (() => logger.InvokeSelf(output)));
				}
				else
				{
					logger.InvokeSelf(output);
				}
			}
		}
	}
}

Awesome, works like a charm thanks!

This is a live saver. Thank you!