I feel confident an productive with LAMP and the Open Web/HTML5, and have been building some cool apps with them, mostly as a freelance developer. I wanna lear

I feel confident an productive with LAMP and the Open Web/HTML5, and have been building some cool apps with them, mostly as a freelance developer. I wanna learn something new mostly to stop feeling that I might be missing something cooler than building webapps, and to make me a better programmer (also for webapps) by using other language/community's concepts and best-practicies.