QR Codes originated in Japan to tag auto parts, but have expanded to become a way for mobile users with cameraphones to quickly link to online content from print ads, products, magazines, you name it (including booth girls at tech conferences, and Matt Joneses eternal struggle to get a 2D code into icons and all else). Fully half of all i-mode users in Japan have used QR codes, according to RFID in Japan.
So, Kaywa has created a QR code reader that fits nicely in your mobile, and also a code generator so you can create your own code. You can also test it on a few sample codes on their site as well, and download some music if you are so cool as to be in Switzerland, where they are based.
Visit qrcode.kaywa.com to generate a QR code for your URL, text, phone number or text message. The QR code on the side was generated there for this blog.