Weather information, stock market trends, gmail unread emails count, battery charge level, Facebook unseen notifications and more can be at your OSX StatusBar. But the most important is that: you can build your own monitoring triggers by your self! And YES, it’s FREE!

Source: ShellWrangler – DIY monitoring tool
For further reading: DIY your menubar application! Don’t waste $ for what is already available for free. (Mac Rumors)